Middle School Science Quiz: Build And Test Heat Device

20 questions · exam conditions

0:00

Build And Test Heat DeviceQuestion 1 of 20

A thermos was constructed with a double wall, a vacuum layer between the walls, a reflective coating, and a tightly sealed cap. To test it, a student poured in coffee at $75^\circ\text{C}$ , sealed the cap, left it in a $22^\circ\text{C}$ room, and measured the coffee temperature every 2 hours.

Data: 0 hr: $75^\circ\text{C}$ , 2 hr: $72^\circ\text{C}$ , 4 hr: $68^\circ\text{C}$ , 6 hr: $65^\circ\text{C}$ , 8 hr: $62^\circ\text{C}$ .

Criterion: maintain $\ge 60^\circ\text{C}$ for 8 hours.

What is the correct evaluation of the thermos test?

Fail, because the temperature decreased over time.

Pass, because at 8 hours the temperature was

62^\circ\text{C}

, which is above

60^\circ\text{C}

Fail, because

62^\circ\text{C}

is below the starting temperature of

75^\circ\text{C}

Fail, because the criterion is to stay at exactly

60^\circ\text{C}

for 8 hours.

← Back to quizzes

Middle School Science Quiz

Middle School Science Quiz: Build And Test Heat Device

Practice Build And Test Heat Device in Middle School Science with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Build And Test Heat Device, giving you a quick way to practice the rules, question types, and explanations that matter most for Middle School Science.

How to use this quiz

Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

All questions

Question 1

Data: 0 hr: $75^\circ\text{C}$ , 2 hr: $72^\circ\text{C}$ , 4 hr: $68^\circ\text{C}$ , 6 hr: $65^\circ\text{C}$ , 8 hr: $62^\circ\text{C}$ .

Criterion: maintain $\ge 60^\circ\text{C}$ for 8 hours.

What is the correct evaluation of the thermos test?

Fail, because the temperature decreased over time.
Pass, because at 8 hours the temperature was $62^\circ\text{C}$ , which is above $60^\circ\text{C}$ . (correct answer)
Fail, because $62^\circ\text{C}$ is below the starting temperature of $75^\circ\text{C}$ .
Fail, because the criterion is to stay at exactly $60^\circ\text{C}$ for 8 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a thermos involves: (1) setting up test (add coffee at 75°C starting temperature), (2) sealing device properly (tightly sealed cap), (3) placing in test environment (22°C room), (4) measuring performance over time (temperature every 2 hours), (5) recording data (temperature vs time), and (6) comparing results to criteria (at 8 hours, is temperature ≥ 60°C?). The thermos test shows: 75°C (start) → 72°C (2 hr) → 68°C (4 hr) → 65°C (6 hr) → 62°C (8 hr), and criterion is "maintain ≥60°C for 8 hours"—at 8 hours, measured 62°C exceeds required 60°C (62 > 60), so criterion MET ✓ successfully. The performance shows: (1) slow cooling rate (~1.6°C per hour: 75°C to 62°C in 8 hrs = 13°C drop / 8 hrs), indicating excellent insulation, (2) temperature stays well above minimum throughout (never even close to failing: lowest is 62°C, comfortably above 60°C threshold), and (3) design features working (vacuum gap preventing conduction/convection, reflective surfaces minimizing radiation, sealed cap preventing air exchange—all contributing to minimal heat loss). Choice B is correct because it accurately states that at 8 hours the temperature was 62°C, which is above the required 60°C minimum, thus meeting the criterion. Choice A incorrectly claims failure just because temperature decreased (all hot things cool down—the question is whether it stays above threshold); Choice C wrongly compares to starting temperature instead of criterion; Choice D misunderstands the criterion as maintaining exactly 60°C rather than ≥60°C. The success validates the design approach and confirms that addressing all three heat transfer methods creates effective insulation.

Question 2

Three containers were tested with the same hot water starting at $70^\circ\text{C}$ in a $22^\circ\text{C}$ room. After 1 hour, the temperatures were:

Container A (no insulation): $30^\circ\text{C}$ Container B (foam insulation): $55^\circ\text{C}$ Container C (thick foam + sealed lid): $63^\circ\text{C}$

Criterion: after 1 hour, temperature must be $\ge 60^\circ\text{C}$ .

Which container(s) meet the criterion?

Only Container C, because $63^\circ\text{C} \ge 60^\circ\text{C}$ . (correct answer)
Only Container B, because foam insulation always meets $\ge 60^\circ\text{C}$ .
Containers B and C, because both are above $50^\circ\text{C}$ .
All three containers, because they all started at $70^\circ\text{C}$ .

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at 70°C to each container), (2) sealing devices as designed, (3) placing in test environment (22°C room), (4) measuring performance at specified time (1 hour), (5) recording data (temperature for each container), and (6) comparing results to criteria (at 1 hour—is temperature ≥ 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The test results show: Container A (no insulation) = 30°C, Container B (foam insulation) = 55°C, Container C (thick foam + sealed lid) = 63°C—comparing each to criterion "≥60°C at 1 hour": A: 30°C < 60°C (FAIL), B: 55°C < 60°C (FAIL), C: 63°C ≥ 60°C (PASS), so only Container C meets the criterion. Choice A is correct because it accurately identifies that only Container C meets the criterion, with its temperature of 63°C being greater than or equal to the required 60°C. Choice B incorrectly assumes foam insulation automatically guarantees success, when the data clearly show Container B at 55°C fails the ≥60°C requirement; Choice C uses the wrong threshold (50°C instead of 60°C), which would incorrectly pass Container B; Choice D focuses on starting temperature rather than the 1-hour measurement that determines success or failure. The results demonstrate the importance of design features: Container A with no insulation lost 40°C in 1 hour (70°C to 30°C), Container B with basic foam lost 15°C (70°C to 55°C), while Container C with thick foam AND sealed lid lost only 7°C (70°C to 63°C)—showing that multiple insulation strategies working together (thick insulation + proper sealing) are needed to meet stringent criteria. Understanding comparative testing helps identify which design features contribute most to success.

Question 3

A student built a thermos with a double wall, a vacuum gap, a reflective coating, and a tightly sealed cap. They filled it with coffee at $75^\circ\text{C}$ and measured temperature every 2 hours for 8 hours:

0 hr: $75^\circ\text{C}$ 2 hr: $72^\circ\text{C}$ 4 hr: $68^\circ\text{C}$ 6 hr: $65^\circ\text{C}$ 8 hr: $62^\circ\text{C}$

Criterion: maintain $\ge 60^\circ\text{C}$ for 8 hours.

Did this thermos design meet the criterion?

Fail, because the temperature dropped at all, so it did not maintain heat.
Pass, because at 8 hours it was $62^\circ\text{C}$ , which is above $60^\circ\text{C}$ . (correct answer)
Fail, because at 6 hours it was $65^\circ\text{C}$ and the criterion is exactly $60^\circ\text{C}$ .
Fail, because it must stay at $75^\circ\text{C}$ for 8 hours to pass.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature 75°C), (2) sealing device properly (tightly sealed cap), (3) placing in test environment, (4) measuring performance over time (thermometer readings every 2 hours), (5) recording data (temperature vs time), and (6) comparing results to criteria (at 8 hours—is temperature ≥ 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The thermos test shows: 75°C (start) → 72°C (2 hr) → 68°C (4 hr) → 65°C (6 hr) → 62°C (8 hr), and criterion is "maintain ≥60°C for 8 hours"—at 8 hours, measured 62°C exceeds required 60°C (62 > 60), so criterion MET ✓ successfully. Choice B is correct because it accurately compares the 8-hour temperature (62°C) to the criterion (≥60°C), correctly determining that 62°C > 60°C means the criterion is met. Choice A incorrectly claims failure just because temperature dropped at all, misunderstanding that some cooling is expected—the criterion is about maintaining above a threshold, not preventing any temperature change; Choice C misreads both the data (using 6-hour reading) and criterion (claiming it requires exactly 60°C when it's ≥60°C); Choice D completely misunderstands the criterion, thinking it requires maintaining the starting temperature rather than staying above 60°C. The performance shows: (1) slow cooling rate (~1.6°C per hour: 75°C to 62°C in 8 hrs = 13°C drop / 8 hrs), indicating excellent insulation, (2) temperature stays well above minimum throughout (lowest is 62°C, comfortably above 60°C threshold), and (3) design features working (vacuum gap preventing conduction/convection, reflective surfaces minimizing radiation, sealed cap preventing air exchange). The success validates the design approach and confirms that addressing all three heat transfer methods creates effective insulation.

Question 4

A student built an insulated cup using a foam cup with 0.5 cm thick walls and a plastic lid that was placed on top but not sealed tightly (no reflective coating). For the test, the student poured hot water at 70°C into the cup, put the lid on, left it in a 22°C room, and measured the water temperature each hour with a thermometer (±1°C).

Measured temperatures:

0 hr: 70°C
1 hr: 58°C
2 hr: 48°C
3 hr: 40°C

Criterion: Maintain a temperature of at least 60°C for 3 hours.

Did the cup meet the criterion (pass/fail)?

Pass, because the temperature started above 60°C at 0 hr.
Pass, because 58°C at 1 hr is close enough to 60°C.
Fail, because the temperature was already below 60°C at 1 hr (58°C), so it did not stay ≥60°C for 3 hours. (correct answer)
Pass, because the temperature stayed above 40°C for 3 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature like 70°C), (2) sealing device properly (lid on, closed as intended for use), (3) placing in test environment (room temperature), (4) measuring performance over time (use thermometer at intervals: every hour), (5) recording data (temperature vs time), and (6) comparing results to criteria (at the required time—say 3 hours—is measured temperature ≥ required minimum like 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The insulated cup test data show temperature measurements at 0, 1, 2, and 3 hours: 70°C (start), 58°C (1 hr), 48°C (2 hr), 40°C (3 hr)—comparing to the criterion "maintain ≥60°C for 3 hours" reveals failure: at 1 hour, measured temperature is already 58°C but required is ≥60°C, so 58 < 60 means criterion NOT MET (failed immediately at 1 hour). Choice C is correct because it accurately identifies that the temperature was already below 60°C at 1 hour (58°C), so it did not stay ≥60°C for the required 3 hours—the criterion requires maintaining at least 60°C throughout the entire 3-hour period, not just at the end. Choice A incorrectly focuses on starting temperature when the criterion is about maintaining temperature; Choice B wrongly accepts "close enough" when criterion is a threshold (58°C is not acceptable for ≥60°C requirement); Choice D misunderstands the criterion by using wrong threshold (40°C instead of 60°C). The failure indicates: (1) insulation insufficient (0.5 cm foam too thin), (2) lid not sealing (allowing convection heat loss), or (3) no radiation control—improvements needed include thicker insulation, better-sealing lid, or reflective coating to slow heat loss. Real testing requires objective comparison to criteria: if the requirement is ≥60°C for 3 hours, then the temperature must remain at or above 60°C for the entire duration, not just part of it.

Question 5

A student tested a cooler they built from a plastic box with 3 cm foam walls, a sealed lid with a gasket, and a white exterior. They put 1.0 kg of ice at $0^\circ\text{C}$ inside and left it in $25^\circ\text{C}$ air. They measured the ice mass remaining:

0 hr: 1000 g 2 hr: 920 g 4 hr: 840 g 6 hr: 760 g

Criterion: after 6 hours, at least 800 g of ice must remain (meaning $\le 200$ g may melt).

Based on the data, did the cooler meet the criterion?

Yes (pass), because 760 g is more than half of 1000 g.
Yes (pass), because only 160 g melted by 4 hours.
No (fail), because 240 g melted by 6 hours (1000 g − 760 g = 240 g), which is more than the 200 g allowed. (correct answer)
No (fail), because the criterion requires all 1000 g to stay frozen.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add cold ice at 0°C), (2) sealing device properly (lid with gasket, closed as intended), (3) placing in test environment (25°C air), (4) measuring performance over time (mass of ice at intervals: every 2 hours), (5) recording data (ice mass remaining vs time), and (6) comparing results to criteria (at 6 hours—is ice mass remaining ≥ 800 g? if yes, criterion met ✓; if no, criterion failed ✗). Testing cooler with 1 kg ice shows mass remaining: 1000 g (start), 920 g at 2 hr (80 g melted), 840 g at 4 hr (160 g melted), 760 g at 6 hr (240 g melted), compared to criterion "at least 800 g must remain" (or equivalently ≤200 g may melt)—at 6 hours, only 760 g ice remains, meaning 240 g melted (1000 g - 760 g = 240 g), which is 240 > 200 so FAILED criterion (exceeded allowed melting by 40 g). Choice C is correct because it accurately calculates the amount melted (1000 g - 760 g = 240 g) and correctly compares this to the criterion (240 g > 200 g allowed), determining the cooler failed. Choice A incorrectly evaluates based on "more than half" remaining rather than the specific criterion; Choice B uses the wrong time point (4 hours instead of 6 hours); Choice D misinterprets the criterion as requiring all ice to stay frozen when it allows up to 200 g to melt. The melting rate is ~40 g per hour (240 g / 6 hr), indicating heat gain of ~40 g × 334 J/g ≈ 13,400 J per hour entering cooler—too much heat transfer, need better insulation: thicker walls, better seal, or shade from sun. Real testing validates design effectiveness by providing objective data showing exactly how much the design failed (40 g over limit), guiding specific improvements needed.

Question 6

Measured temperatures:

0 hr: 70°C
1 hr: 58°C
2 hr: 48°C
3 hr: 40°C

Criterion: Maintain a temperature of at least 60°C for 3 hours.

Did the cup meet the criterion (pass/fail)?

Pass, because the temperature started above 60°C at 0 hr.
Pass, because 58°C at 1 hr is close enough to 60°C.
Fail, because the temperature was already below 60°C at 1 hr (58°C), so it did not stay ≥60°C for 3 hours. (correct answer)
Pass, because the temperature stayed above 40°C for 3 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature like 70°C), (2) sealing device properly (lid on, closed as intended for use), (3) placing in test environment (room temperature), (4) measuring performance over time (use thermometer at intervals: every hour), (5) recording data (temperature vs time), and (6) comparing results to criteria (at the required time—say 3 hours—is measured temperature ≥ required minimum like 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The insulated cup test data show temperature measurements at 0, 1, 2, and 3 hours: 70°C (start), 58°C (1 hr), 48°C (2 hr), 40°C (3 hr)—comparing to the criterion "maintain ≥60°C for 3 hours" reveals failure: at 1 hour, measured temperature is already 58°C but required is ≥60°C, so 58 < 60 means criterion NOT MET (failed immediately at 1 hour). Choice C is correct because it accurately identifies that the temperature was already below 60°C at 1 hour (58°C), so it did not stay ≥60°C for the required 3 hours—the criterion requires maintaining at least 60°C throughout the entire 3-hour period, not just at the end. Choice A incorrectly focuses on starting temperature when the criterion is about maintaining temperature; Choice B wrongly accepts "close enough" when criterion is a threshold (58°C is not acceptable for ≥60°C requirement); Choice D misunderstands the criterion by using wrong threshold (40°C instead of 60°C). The failure indicates: (1) insulation insufficient (0.5 cm foam too thin), (2) lid not sealing (allowing convection heat loss), or (3) no radiation control—improvements needed include thicker insulation, better-sealing lid, or reflective coating to slow heat loss. Real testing requires objective comparison to criteria: if the requirement is ≥60°C for 3 hours, then the temperature must remain at or above 60°C for the entire duration, not just part of it.

Question 7

A thermos was constructed with a double wall, a vacuum layer between walls, a reflective inner coating, and a tightly sealed screw cap. Test procedure: Coffee at 75°C was poured in, the cap was sealed, the thermos was kept in a 21°C room, and temperature was measured every 2 hours.

Data:

0 hr: 75°C
2 hr: 72°C
4 hr: 68°C
6 hr: 65°C
8 hr: 62°C

Criterion: Maintain at least 60°C for 8 hours.

Did the thermos meet the criterion?

Fail, because the temperature decreased over time.
Fail, because 62°C is below 75°C.
Pass, because at 8 hours the temperature was 62°C, which is ≥60°C. (correct answer)
Fail, because the temperature dropped below 65°C at 8 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature like 75°C), (2) sealing device properly (screw cap tightly sealed), (3) placing in test environment (room temperature), (4) measuring performance over time (use thermometer at intervals: every 2 hours), (5) recording data (temperature vs time), and (6) comparing results to criteria (at 8 hours—is measured temperature ≥ required minimum 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The thermos test shows: 75°C (start) → 72°C (2 hr) → 68°C (4 hr) → 65°C (6 hr) → 62°C (8 hr), and criterion is "maintain at least 60°C for 8 hours"—at 8 hours, measured 62°C exceeds required 60°C (62 > 60), so criterion MET ✓ successfully. Choice C is correct because it accurately compares the 8-hour temperature (62°C) to the criterion (≥60°C) and correctly determines the thermos passed. Choice A incorrectly assumes any temperature decrease means failure (when criterion allows decrease as long as stays ≥60°C); Choice B compares to wrong value (75°C starting temperature instead of 60°C criterion); Choice D uses wrong threshold (65°C instead of 60°C). The performance shows: (1) slow cooling rate (~1.6°C per hour: 75°C to 62°C in 8 hrs = 13°C drop / 8 hrs), indicating excellent insulation, (2) temperature stays well above minimum throughout (lowest is 62°C, comfortably above 60°C threshold), and (3) design features working (vacuum gap preventing conduction/convection, reflective surfaces minimizing radiation, sealed cap preventing air exchange). The success validates the design approach and confirms that addressing all three heat transfer methods creates effective insulation.

Question 8

A cooler (plastic box, 3 cm foam walls, gasket-sealed lid, white exterior) was tested with 1000 g of ice at 0°C in a 25°C room. Ice mass remaining:

0 hr: 1000 g
2 hr: 920 g
4 hr: 840 g
6 hr: 760 g

Criterion: No more than 200 g of ice may melt in 6 hours.

How much ice melted by 6 hours, and does that meet the criterion?

240 g melted; does NOT meet the criterion. (correct answer)
760 g melted; does NOT meet the criterion.
200 g melted; meets the criterion.
160 g melted; meets the criterion.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add 1000 g ice at 0°C), (2) sealing device properly (gasket-sealed lid), (3) placing in test environment (25°C room), (4) measuring performance over time (ice mass every 2 hours), (5) recording data (ice remaining vs time), and (6) comparing results to criteria (no more than 200 g melted in 6 hours). Calculating ice melted: started with 1000 g, ended with 760 g at 6 hours, so ice melted = 1000 g - 760 g = 240 g—comparing to criterion "no more than 200 g may melt," we find 240 g > 200 g, so criterion NOT MET (exceeded allowed melting by 40 g). Choice A is correct because it accurately calculates that 240 g melted (1000 - 760 = 240) and correctly determines this does NOT meet the criterion since 240 > 200. Choice B incorrectly states 760 g melted (that's the amount remaining, not melted); Choice C incorrectly calculates 200 g melted when actually 240 g melted; Choice D incorrectly calculates 160 g melted (that was at 4 hours: 1000 - 840 = 160, not at 6 hours). The melting progression shows: 80 g melted by 2 hr, 160 g by 4 hr, 240 g by 6 hr—a steady rate of 40 g per hour, indicating consistent heat gain despite insulation. Understanding ice melting calculations: always subtract final mass from initial mass to find amount melted (not the reverse), and compare melted amount (not remaining amount) to criterion when stated as maximum melt allowed.

Question 9

A thermos (double-wall vacuum, reflective coating, sealed cap) was tested with coffee starting at 75°C in a 21°C room. Data:

0 hr: 75°C
2 hr: 72°C
4 hr: 68°C
6 hr: 65°C
8 hr: 62°C

Criterion: Maintain ≥60°C for 8 hours.

By how many degrees did the thermos exceed the minimum required temperature at 8 hours?

2°C (correct answer)
13°C
60°C
−2°C (it was below the requirement)

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot coffee at 75°C), (2) sealing device properly (sealed cap), (3) placing in test environment (21°C room), (4) measuring performance over time (every 2 hours), (5) recording data (temperature vs time), and (6) comparing results to criteria (at 8 hours, is temperature ≥60°C?). The thermos maintained 62°C at 8 hours, and the criterion requires ≥60°C—to find how much it exceeded the minimum: 62°C (actual) - 60°C (minimum required) = 2°C excess above threshold. Choice A is correct because it accurately calculates that the thermos exceeded the minimum by 2°C (62°C - 60°C = 2°C). Choice B incorrectly calculates 13°C (possibly 75 - 62 = 13, which is total drop, not excess above minimum); Choice C incorrectly uses 60°C (that's the minimum requirement, not the excess); Choice D incorrectly suggests negative value when thermos actually exceeded (not fell below) the requirement. The 2°C margin shows: (1) thermos successfully met criterion with small buffer, (2) design is adequate but not excessive (efficient use of materials), and (3) in real use, provides slight safety margin for measurement uncertainty or slightly worse conditions. Understanding margin calculations: when evaluating pass/fail with threshold criteria, calculate how much above (positive) or below (negative) the threshold—here, positive 2°C confirms successful performance.

Question 10

A student tested a homemade cooler made from a plastic box with 3 cm foam walls, a sealed lid with a rubber gasket, and a white exterior. Test procedure: Put 1.0 kg of ice (1000 g) at 0°C inside, closed the lid, kept it in a 25°C room, and measured how much ice mass remained every 2 hours.

Data (ice mass remaining):

0 hr: 1000 g
2 hr: 920 g
4 hr: 840 g
6 hr: 760 g

Criterion: Keep at least 800 g of ice frozen after 6 hours (meaning no more than 200 g melted).

Which statement correctly evaluates the result?

Pass, because 760 g is greater than 700 g.
Fail, because only 760 g remained at 6 hr, which is below the required 800 g. (correct answer)
Pass, because the cooler still had ice at 6 hr.
Pass, because only 160 g melted by 6 hr.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add cold ice at 0°C), (2) sealing device properly (lid with gasket, closed as intended), (3) placing in test environment (room temperature), (4) measuring performance over time (measure ice mass at intervals: every 2 hours), (5) recording data (ice mass remaining vs time), and (6) comparing results to criteria (at 6 hours—is ice mass remaining ≥ required minimum like 800 g? if yes, criterion met ✓; if no, criterion failed ✗). Testing cooler with 1 kg ice shows mass remaining: 1000 g (start), 920 g at 2 hr (80 g melted), 840 g at 4 hr (160 g melted), 760 g at 6 hr (240 g melted), compared to criterion "keep at least 800 g of ice frozen after 6 hours" (or equivalently no more than 200 g melted)—at 6 hours, only 760 g ice remains, which is 760 < 800 so FAILED criterion (fell short by 40 g). Choice B is correct because it accurately compares measured performance to criterion: only 760 g remained at 6 hr, which is below the required 800 g minimum. Choice A incorrectly compares to wrong threshold (700 g instead of 800 g); Choice C ignores quantitative criterion and uses qualitative assessment ("still had ice" doesn't mean criterion met); Choice D miscalculates melted amount (claims 160 g when actually 240 g melted: 1000 - 760 = 240). The melting rate is ~40 g per hour (240 g / 6 hr), indicating heat gain entering cooler—too much heat transfer despite 3 cm foam walls and sealed lid. Understanding testing importance: verifies design works (or doesn't—data reveals inadequate performance), identifies problems objectively (failed by 40 g), and guides improvements (need better insulation or reduced heat gain).

Question 11

A cooler (plastic box, 3 cm foam walls, gasket-sealed lid) was tested with 1000 g ice at 0°C in a 25°C room. Ice mass remaining was 920 g at 2 hours and 840 g at 4 hours.

Criterion: Keep at least 800 g of ice after 6 hours.

Based on the melting trend from 0 to 4 hours, which prediction is most reasonable for 6 hours, and would it meet the criterion?

About 760 g remaining; it would NOT meet the 800 g criterion. (correct answer)
About 880 g remaining; it would meet the 800 g criterion.
About 1000 g remaining; it would meet the 800 g criterion.
About 840 g remaining; it would NOT meet the 800 g criterion.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing involves analyzing trends to predict future performance—the cooler data show ice remaining: 1000 g (start), 920 g at 2 hr (80 g melted), 840 g at 4 hr (160 g melted), revealing a consistent melting rate of 40 g per hour (80 g in 2 hr = 40 g/hr, verified by 160 g in 4 hr = 40 g/hr). Extrapolating this constant rate to 6 hours: 40 g/hr × 6 hr = 240 g total melted, so ice remaining = 1000 g - 240 g = 760 g—comparing to criterion "keep at least 800 g," we find 760 g < 800 g, so would NOT meet criterion. Choice A is correct because it accurately predicts 760 g remaining based on the linear melting trend (1000 - 240 = 760) and correctly determines this would NOT meet the 800 g criterion. Choice B incorrectly predicts 880 g (would require only 120 g melted, inconsistent with 40 g/hr rate); Choice C unrealistically predicts no melting beyond 4 hours; Choice D uses the 4-hour value instead of extrapolating to 6 hours. The linear melting rate (constant 40 g/hr) indicates steady-state heat transfer: heat gain through insulation equals heat absorbed by melting ice, suggesting the cooler has reached thermal equilibrium with consistent performance. Understanding trend analysis: when data shows linear behavior (constant rate), extrapolation is reliable for near-term predictions—here, the consistent 40 g/hr rate from 0-4 hours reasonably extends to 6 hours.

Question 12

Data (ice mass remaining):

0 hr: 1000 g
2 hr: 920 g
4 hr: 840 g
6 hr: 760 g

Criterion: Keep at least 800 g of ice frozen after 6 hours (meaning no more than 200 g melted).

Which statement correctly evaluates the result?

Pass, because 760 g is greater than 700 g.
Fail, because only 760 g remained at 6 hr, which is below the required 800 g. (correct answer)
Pass, because the cooler still had ice at 6 hr.
Pass, because only 160 g melted by 6 hr.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add cold ice at 0°C), (2) sealing device properly (lid with gasket, closed as intended), (3) placing in test environment (room temperature), (4) measuring performance over time (measure ice mass at intervals: every 2 hours), (5) recording data (ice mass remaining vs time), and (6) comparing results to criteria (at 6 hours—is ice mass remaining ≥ required minimum like 800 g? if yes, criterion met ✓; if no, criterion failed ✗). Testing cooler with 1 kg ice shows mass remaining: 1000 g (start), 920 g at 2 hr (80 g melted), 840 g at 4 hr (160 g melted), 760 g at 6 hr (240 g melted), compared to criterion "keep at least 800 g of ice frozen after 6 hours" (or equivalently no more than 200 g melted)—at 6 hours, only 760 g ice remains, which is 760 < 800 so FAILED criterion (fell short by 40 g). Choice B is correct because it accurately compares measured performance to criterion: only 760 g remained at 6 hr, which is below the required 800 g minimum. Choice A incorrectly compares to wrong threshold (700 g instead of 800 g); Choice C ignores quantitative criterion and uses qualitative assessment ("still had ice" doesn't mean criterion met); Choice D miscalculates melted amount (claims 160 g when actually 240 g melted: 1000 - 760 = 240). The melting rate is ~40 g per hour (240 g / 6 hr), indicating heat gain entering cooler—too much heat transfer despite 3 cm foam walls and sealed lid. Understanding testing importance: verifies design works (or doesn't—data reveals inadequate performance), identifies problems objectively (failed by 40 g), and guides improvements (need better insulation or reduced heat gain).

Question 13

A student compared three containers for keeping water hot. Each started with 70°C water, was closed, left in the same 22°C room, and measured after 1 hour.

Container A (no insulation): 70°C → 30°C in 1 hour
Container B (foam insulation): 70°C → 55°C in 1 hour
Container C (thick foam + sealed lid): 70°C → 63°C in 1 hour

Criterion: After 1 hour, temperature must be at least 60°C.

Which container(s) meet the criterion?

Only Container A
Only Container B
Only Container C (correct answer)
Containers B and C

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at 70°C to each container), (2) sealing device properly (close each as designed), (3) placing in test environment (same 22°C room for fair comparison), (4) measuring performance over time (temperature after 1 hour), (5) recording data (final temperature for each), and (6) comparing results to criteria (after 1 hour, is temperature ≥60°C? if yes, criterion met ✓; if no, criterion failed ✗). Comparing three containers: Container A (no insulation) dropped from 70°C to 30°C (40°C loss), Container B (foam insulation) dropped to 55°C (15°C loss), Container C (thick foam + sealed lid) dropped to 63°C (7°C loss)—criterion requires ≥60°C after 1 hour, so Container A at 30°C fails (30 < 60), Container B at 55°C fails (55 < 60), but Container C at 63°C passes (63 > 60). Choice C is correct because only Container C meets the criterion with its 63°C temperature exceeding the 60°C minimum requirement. Choice A incorrectly selects Container A which dramatically failed (30°C is far below 60°C); Choice B incorrectly selects Container B which also failed (55°C < 60°C); Choice D incorrectly includes Container B which didn't meet the criterion. The results demonstrate insulation effectiveness: no insulation loses 40°C/hour (catastrophic heat loss), foam alone reduces to 15°C/hour loss (better but insufficient), while thick foam + sealed lid achieves only 7°C/hour loss (adequate for criterion). Understanding comparative testing: tests multiple designs under identical conditions to identify which meets requirements and reveals how design features (insulation thickness, lid sealing) directly impact performance.

Question 14

Data:

0 hr: 75°C
2 hr: 72°C
4 hr: 68°C
6 hr: 65°C
8 hr: 62°C

Criterion: Maintain at least 60°C for 8 hours.

Did the thermos meet the criterion?

Fail, because the temperature decreased over time.
Fail, because 62°C is below 75°C.
Pass, because at 8 hours the temperature was 62°C, which is ≥60°C. (correct answer)
Fail, because the temperature dropped below 65°C at 8 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature like 75°C), (2) sealing device properly (screw cap tightly sealed), (3) placing in test environment (room temperature), (4) measuring performance over time (use thermometer at intervals: every 2 hours), (5) recording data (temperature vs time), and (6) comparing results to criteria (at 8 hours—is measured temperature ≥ required minimum 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The thermos test shows: 75°C (start) → 72°C (2 hr) → 68°C (4 hr) → 65°C (6 hr) → 62°C (8 hr), and criterion is "maintain at least 60°C for 8 hours"—at 8 hours, measured 62°C exceeds required 60°C (62 > 60), so criterion MET ✓ successfully. Choice C is correct because it accurately compares the 8-hour temperature (62°C) to the criterion (≥60°C) and correctly determines the thermos passed. Choice A incorrectly assumes any temperature decrease means failure (when criterion allows decrease as long as stays ≥60°C); Choice B compares to wrong value (75°C starting temperature instead of 60°C criterion); Choice D uses wrong threshold (65°C instead of 60°C). The performance shows: (1) slow cooling rate (~1.6°C per hour: 75°C to 62°C in 8 hrs = 13°C drop / 8 hrs), indicating excellent insulation, (2) temperature stays well above minimum throughout (lowest is 62°C, comfortably above 60°C threshold), and (3) design features working (vacuum gap preventing conduction/convection, reflective surfaces minimizing radiation, sealed cap preventing air exchange). The success validates the design approach and confirms that addressing all three heat transfer methods creates effective insulation.

Question 15

A student built an insulated cup using a foam cup with 0.5 cm thick walls and a plastic lid that was not sealed tightly (no reflective coating). They poured in hot water at $70^\circ\text{C}$ , put the lid on, and left it in a room at about $22^\circ\text{C}$ . They measured the water temperature every hour:

Time 0 hr: $70^\circ\text{C}$ 1 hr: $58^\circ\text{C}$ 2 hr: $48^\circ\text{C}$ 3 hr: $40^\circ\text{C}$

Criterion: maintain a temperature of at least $\ge 60^\circ\text{C}$ for 3 hours.

Did the insulated cup meet the criterion (pass) or not (fail)?

Pass, because it started at $70^\circ\text{C}$ which is above $60^\circ\text{C}$ .
Fail, because it was already below $60^\circ\text{C}$ at 1 hour ( $58^\circ\text{C}$ ), so it could not stay $\ge 60^\circ\text{C}$ for 3 hours. (correct answer)
Pass, because $40^\circ\text{C}$ at 3 hours is close enough to $60^\circ\text{C}$ .
Pass, because the criterion only matters at 0 hours and it was $70^\circ\text{C}$ then.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature like 70°C), (2) sealing device properly (lid on, closed as intended for use), (3) placing in test environment (room temperature), (4) measuring performance over time (use thermometer at intervals: every hour), (5) recording data (temperature vs time), and (6) comparing results to criteria (at the required time—3 hours—is measured temperature ≥ required minimum 60°C? if yes, criterion met ✓; if no, criterion failed ✗). The insulated cup test data show temperature measurements at 0, 1, 2, and 3 hours: 70°C (start), 58°C (1 hr), 48°C (2 hr), 40°C (3 hr)—comparing to the criterion "maintain ≥60°C for 3 hours" reveals failure: at 1 hour, the temperature had already dropped to 58°C (below 60°C), meaning the device could not possibly maintain ≥60°C for the full 3 hours. Choice B is correct because it accurately identifies that the device failed by noting the temperature was already below 60°C at 1 hour (58°C < 60°C), making it impossible to meet the 3-hour criterion. Choice A incorrectly focuses on the starting temperature rather than whether it was maintained; Choice C wrongly accepts 40°C as "close enough" when the criterion requires ≥60°C (40°C is 20°C below the threshold—a clear failure); Choice D misunderstands the criterion, which requires maintaining the temperature for the full duration, not just at the start. The failure indicates: (1) insulation insufficient (0.5 cm foam too thin), (2) lid not sealing (allowing convection heat loss), or (3) no radiation control—improvements needed include thicker insulation, better-sealing lid, or reflective coating to slow heat loss. Understanding testing importance: verifies design works (or doesn't—data reveals inadequate performance), identifies problems objectively (temperature dropped too quickly), and guides improvements (need better insulation and sealing).

Question 16

A student tested a cooler (plastic box, 3 cm foam walls, gasket-sealed lid, white exterior) with 1000 g of ice at $0^\circ\text{C}$ in $25^\circ\text{C}$ air. Ice mass remaining:

0 hr: 1000 g 2 hr: 920 g 4 hr: 840 g 6 hr: 760 g

Criterion: at least 800 g must remain after 6 hours.

Which statement best describes what the test results show?

The cooler succeeded because it still had ice left at 6 hours (760 g).
The cooler failed because at 6 hours it had 760 g remaining, which is below the required 800 g. (correct answer)
The cooler succeeded because it melted exactly 200 g by 6 hours.
The cooler failed because it must keep the ice below $0^\circ\text{C}$ , and the data show the temperature rose above $0^\circ\text{C}$ .

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing involves measuring ice mass over time and comparing to the criterion—the cooler must have at least 800 g remaining after 6 hours, but the data show only 760 g remains. The cooler started with 1000 g ice and had 760 g remaining at 6 hours, meaning 240 g melted; since the criterion requires at least 800 g to remain (allowing maximum 200 g to melt), having only 760 g means the cooler failed by 40 g (800 g required - 760 g actual = 40 g shortfall). Choice B is correct because it accurately states the cooler failed, correctly identifying that 760 g remaining is below the required 800 g minimum. Choice A incorrectly claims success just because some ice remained, ignoring the specific 800 g threshold; Choice C incorrectly states exactly 200 g melted when actually 240 g melted (1000 g - 760 g = 240 g); Choice D introduces an irrelevant criterion about temperature when the test only measures ice mass, not temperature. The failure by 40 g (or 5% below the required amount) indicates the cooler's insulation is close but not quite adequate—the melting rate of 40 g/hour means heat is entering at about 13,400 J/hour, suggesting improvements like thicker foam walls or better lid sealing could achieve the needed 17% reduction in heat transfer. Clear interpretation of test results against specific criteria is essential for objective evaluation and targeted improvements.

Question 17

A student built an insulated cup using a foam cup with 0.5 cm-thick walls and a plastic lid that was not sealed tightly (no reflective coating). For the test, the student poured hot water at $70^\circ\text{C}$ into the cup, put the lid on, left it in a $25^\circ\text{C}$ room, and measured the water temperature each hour with a thermometer (± $1^\circ\text{C}$ ).

Data: 0 hr: $70^\circ\text{C}$ , 1 hr: $58^\circ\text{C}$ , 2 hr: $48^\circ\text{C}$ , 3 hr: $40^\circ\text{C}$ .

Criterion: maintain temperature $\ge 60^\circ\text{C}$ for 3 hours.

Did the insulated cup meet the criterion (pass or fail)?

Pass, because the water started at $70^\circ\text{C}$ which is above $60^\circ\text{C}$ .
Fail, because at 1 hour the temperature was $58^\circ\text{C}$ , which is below the required $60^\circ\text{C}$ . (correct answer)
Pass, because $40^\circ\text{C}$ at 3 hours is close enough to $60^\circ\text{C}$ .
Pass, because the temperature stayed above $50^\circ\text{C}$ for 2 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a heat device involves: (1) setting up test (add hot liquid at measured starting temperature like 70°C), (2) sealing device properly (lid on, though this one wasn't sealed tightly), (3) placing in test environment (25°C room), (4) measuring performance over time (thermometer readings every hour), (5) recording data (temperature vs time), and (6) comparing results to criteria (at 3 hours, is measured temperature ≥ 60°C?). The insulated cup test data show temperature measurements at 0, 1, 2, and 3 hours: 70°C (start), 58°C (1 hr), 48°C (2 hr), 40°C (3 hr)—comparing to the criterion "maintain ≥60°C for 3 hours" reveals failure: at 3 hours, measured temperature is 40°C but required is ≥60°C, so 40 < 60 means criterion NOT MET (failed by 20°C—significantly below threshold). Even at 1 hour, the device had already fallen to 58°C (below 60°C), demonstrating inadequate insulation with a heat loss rate of ~10°C per hour when needed to lose <3.3°C per hour to maintain 60°C at 3 hours. Choice B is correct because it accurately identifies that the criterion failed at 1 hour when temperature dropped to 58°C, which is below the required 60°C minimum. Choice A incorrectly focuses on starting temperature rather than maintained temperature; Choice C wrongly accepts 40°C as "close enough" when criterion requires ≥60°C (thresholds are absolute, not approximate); Choice D invents a different criterion about 50°C for 2 hours instead of the actual 60°C for 3 hours requirement. The failure indicates: (1) insulation insufficient (0.5 cm foam too thin), (2) lid not sealing properly (allowing convection heat loss as noted in problem), or (3) no radiation control—improvements needed include thicker insulation, better-sealing lid, or reflective coating to slow heat loss.

Question 18

A student tested an insulated cup (foam walls 0.5 cm thick, loose plastic lid) by filling it with $70^\circ\text{C}$ water and measuring temperature each hour in a $25^\circ\text{C}$ room.

Data: 0 hr: $70^\circ\text{C}$ , 1 hr: $58^\circ\text{C}$ , 2 hr: $48^\circ\text{C}$ , 3 hr: $40^\circ\text{C}$ .

Criterion: maintain $\ge 60^\circ\text{C}$ for 3 hours.

Which statement best describes why the design failed based on the construction details and data?

It failed because the lid was not sealed tightly, allowing faster heat loss (convection) so the temperature dropped below $60^\circ\text{C}$ by 1 hour. (correct answer)
It failed because foam is a good conductor, so heat moved into the water and warmed it too much.
It failed because the room temperature was $25^\circ\text{C}$ , which is higher than $0^\circ\text{C}$ .
It failed because the water stayed above $40^\circ\text{C}$ for 3 hours.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing the insulated cup involved: (1) foam walls only 0.5 cm thick (thin insulation), (2) loose plastic lid (not sealed tightly as stated), (3) hot water cooling from 70°C to 58°C in just 1 hour, (4) continued rapid cooling to 48°C (2 hr) and 40°C (3 hr), and (5) failure to meet criterion of ≥60°C for 3 hours (already below 60°C at 1 hour). The data show a cooling rate of ~10°C per hour (70°C to 40°C in 3 hours = 30°C drop / 3 hrs), which is too fast to maintain 60°C—the device needed to lose less than 3.3°C per hour to stay above 60°C at 3 hours. The construction details reveal the problem: loose lid allows convection currents where hot air escapes and cool air enters, thin 0.5 cm foam provides insufficient conduction barrier, and no reflective coating means radiation losses are uncontrolled. Choice A is correct because it accurately identifies that the loose lid allowed faster heat loss through convection, causing the temperature to drop below 60°C by 1 hour (58°C < 60°C). Choice B incorrectly states foam is a good conductor when foam is actually a good insulator (poor conductor); Choice C irrelevantly mentions room temperature without connecting to heat transfer; Choice D makes no sense as staying above 40°C doesn't relate to the failure mechanism. The failure analysis shows that even one poorly controlled heat transfer pathway (convection through loose lid) can cause device failure despite having some insulation (foam walls).

Question 19

A cooler was built from a plastic box with 3 cm foam walls, a sealed lid with a gasket, and a white exterior. To test it, a student put 1.0 kg of ice at $0^\circ\text{C}$ inside, closed the lid, left it in $25^\circ\text{C}$ air, and measured the ice mass remaining every 2 hours.

Data (ice remaining): 0 hr: 1000 g, 2 hr: 920 g, 4 hr: 840 g, 6 hr: 760 g.

Criterion: keep $\ge 800\text{ g}$ of ice frozen after 6 hours (meaning $\le 200\text{ g}$ melted).

Based on the data, did the cooler meet the criterion?

Fail, because only 760 g remained at 6 hours, which is less than the required 800 g. (correct answer)
Pass, because 760 g is more than half of 1000 g.
Pass, because the cooler had thick foam and a gasket, so it must meet the criterion.
Pass, because 240 g melted is less than the allowed 800 g melted.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing a cooler involves: (1) setting up test (add 1.0 kg ice at 0°C), (2) sealing device properly (lid with gasket closed), (3) placing in test environment (25°C air), (4) measuring performance over time (ice mass every 2 hours), (5) recording data (ice mass remaining vs time), and (6) comparing results to criteria (at 6 hours, is ice mass remaining ≥ 800 g?). The cooler test shows mass remaining: 1000 g (start), 920 g at 2 hr (80 g melted), 840 g at 4 hr (160 g melted), 760 g at 6 hr (240 g melted), compared to criterion "≥800 g remaining after 6 hours" (or equivalently ≤200 g melted)—at 6 hours, only 760 g ice remains (240 g melted), which means 760 < 800 so FAILED criterion (40 g short of requirement). The melting rate is ~40 g per hour (240 g / 6 hr), indicating heat gain of ~40 g × 334 J/g ≈ 13,400 J per hour entering cooler—too much heat transfer despite 3 cm foam walls and sealed gasket. Choice A is correct because it accurately compares measured performance (760 g remaining) to criterion (≥800 g required), determining the cooler failed by having 40 g less ice than required. Choice B incorrectly claims success because 760 g is more than half of 1000 g, but the criterion is 800 g not 500 g; Choice C assumes good construction guarantees success without checking data; Choice D confuses the criterion by comparing melted amount (240 g) to remaining amount requirement (800 g) instead of to melted limit (200 g). Real testing requires objective data comparison: the cooler failed despite good design features (3 cm foam, gasket seal, white exterior), suggesting need for even better insulation or reduced test duration.

Question 20

A thermos (double-wall vacuum, reflective coating, sealed cap) was tested with coffee starting at $75^\circ\text{C}$ . Temperatures were recorded:

0 hr: $75^\circ\text{C}$ , 2 hr: $72^\circ\text{C}$ , 4 hr: $68^\circ\text{C}$ , 6 hr: $65^\circ\text{C}$ , 8 hr: $62^\circ\text{C}$ .

Criterion: $\ge 60^\circ\text{C}$ at 8 hours.

What does the data show about the thermos's performance compared to the criterion?

It failed because the temperature dropped 13°C from 0 to 8 hours.
It passed because it was $2^\circ\text{C}$ above the required minimum at 8 hours ( $62^\circ\text{C} > 60^\circ\text{C}$ ). (correct answer)
It failed because it was $2^\circ\text{C}$ below the required minimum at 8 hours.
It passed only if the temperature stayed exactly $75^\circ\text{C}$ the entire time.

Explanation: This question tests understanding of how to test a heat control device and evaluate whether its performance meets the established criteria by comparing measured data to required values. Testing the thermos involved: (1) starting with 75°C coffee, (2) measuring temperature every 2 hours, (3) recording steady decline to 62°C at 8 hours, (4) comparing to criterion of ≥60°C at 8 hours, and (5) determining performance margin. The thermos data show excellent insulation performance: 75°C → 72°C → 68°C → 65°C → 62°C over 8 hours, representing only 13°C total drop (average 1.6°C/hour cooling rate). At the critical 8-hour mark, the temperature is 62°C, which exceeds the required minimum of 60°C by 2°C (62 - 60 = 2°C margin above requirement). The vacuum layer, reflective coating, and sealed cap work together to minimize all three heat transfer modes, resulting in successful performance. Choice B is correct because it accurately states the thermos passed by being 2°C above the required minimum at 8 hours (62°C > 60°C). Choice A incorrectly claims failure based on temperature drop when the criterion is about final temperature not change; Choice C wrongly states 62°C is below 60°C when it's actually above; Choice D misunderstands the criterion as requiring constant 75°C rather than ≥60°C. The 2°C margin shows the design barely met requirements—while successful, there's little safety factor, suggesting the thermos is near its performance limit for this 8-hour criterion.