Practice Test 9 - Middle School Physical Science

20 questions. Answer them in any order, then submit to see your score and every explanation.

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1. A student investigates: How does the starting height of a ball on a ramp affect its speed at the bottom? Which statement correctly matches variable types to this investigation?
2. A cooler was evaluated. Design: 4 cm foam insulation, sealed lid, white exterior. Test results: 850 g ice remaining after 6 hours (started with 1000 g), holds 12 drinks, cost $\45$. Criteria: $\ge 800$ g ice after 6 hours, holds 12 drinks, cost $<\$50$. What is the best overall assessment category for this cooler?
3. A bar magnet is shown with its poles labeled N (left) and S (right). Magnetic field lines are drawn curving through space from N to S, with arrows showing direction. A small compass is placed at point P above the middle of the magnet. Which statement best describes what the field-line model predicts about the compass at point P?
4. Design challenge (solar oven): Your science club is building a solar oven that will absorb solar radiation and convert it to thermal energy to warm food during an outdoor field day. You can only use materials available at home/school (like cardboard, foil, plastic wrap, tape). Which requirement is the best example of a measurable criterion for this solar oven?
5. A pot of water is heated on a stove. After a few minutes, you can see the water moving: warmer water rises and cooler water sinks. Which mechanism is mainly transferring thermal energy through the water, and what is the pathway?
6. Substance A is carbon monoxide ($\mathrm{CO}$), Substance B is carbon dioxide ($\mathrm{CO_2}$), and Substance C is oxygen gas ($\mathrm{O_2}$). Which substance is made of only one element type?
7. A hot soup container loses heat mainly by conduction through its sides. Two designs use the same foam material, but different thicknesses. Which choice will reduce conductive heat loss the most?
8. Iron filings sprinkled near a bar magnet form curved patterns around the magnet. A field-line model shows lines leaving the N pole and entering the S pole, curving through space. How does the field model connect to the iron-filings observation?
9. Two designs were tested against the same requirements (temperature $\ge 60^\circ\text{C}$ after 4 hours; cost <$20). Design A: $58^\circ\text{C}$ after 4 hours; cost $12. Design B: $64^\circ\text{C}$ after 4 hours; cost $18. Which recommendation is best supported by the data?
10. A student uses a Van de Graaff generator. When they touch it, their hair stands up because the hairs repel each other. The student wants an investigable question about what affects the repulsion force. Which question is best?
11. A student is designing a single-use chemical hot pack for warming hands during a winter field trip. The plan is a two-pouch plastic bag: an outer pouch and a small inner water pouch that can be popped by squeezing. When activated, water mixes with a solid chemical and the pack should warm to about 40–60°C. Which chemical is the best choice to include so the pack releases thermal energy when mixed with water?
12. A metal spoon is placed into a cup of hot soup. After a short time, the spoon feels hot. Macroscopic level: the spoon's temperature increases. Which particle-level description best explains why the spoon gets hotter?​
13. A seismograph records two earthquakes. Earthquake 1 produces a small-amplitude trace and causes only minor shaking. Earthquake 2 produces a much larger-amplitude trace and causes more damage. What conclusion is best supported about amplitude and energy?
14. A ball sits in a smooth bowl-shaped track. The lowest point of the bowl is position X. A higher point on either side is position Y. Which statement best explains why position X is a stable equilibrium in terms of force direction and potential energy (PE)?
15. A student wants to improve a hot pack that meets the peak temperature requirement but cools too quickly. Criterion: reach at least $45^\circ\text{C}$ and stay above $40^\circ\text{C}$ for 2 hours. Current test: reaches $47^\circ\text{C}$ but stays above $40^\circ\text{C}$ for only 55 minutes. If the student adds more of the same exothermic chemical (and keeps insulation the same), what is the most likely effect on performance?
16. A group built an instant cold pack by sealing 25 g of ammonium nitrate and 40 mL of water in separate compartments that mix when squeezed. The design criterion is: after activation, the pack should reach $0$ to $5^\circ\text{C}$ within 2 minutes and stay below $10^\circ\text{C}$ for at least 15 minutes. Test results: lowest temperature reached was $15^\circ\text{C}$ at 2 minutes, and it warmed back to $18^\circ\text{C}$ by 10 minutes. Which modification would most directly address the problem shown by the test data?
17. A $2\,\text{kg}$ ball is held at three different heights above the ground: Position G at $0\,\text{m}$, Position B at $2\,\text{m}$, and Position A at $4\,\text{m}$. The gravitational force on the ball points downward. Which statement correctly connects force direction, work, and gravitational potential energy (PE)? (Use $g\approx 10\,\text{N/kg}$.)
18. A football player's helmet has a hard outer shell and a soft foam lining. During a hit, the player's head must slow down from moving to stopping. How does the foam lining help reduce injury?
19. A student sprinkles iron filings on a sheet of paper placed over a bar magnet. The filings form curved lines and are packed more closely near the magnet's ends. What do these observations show about the magnetic field?
20. A graph plots mass (kg) on the x-axis and weight (N) on the y-axis for objects on Earth. Points include (1, 10), (2, 20), and (4, 40). Which statement best describes what the graph would look like?

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