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Physics Quiz

Physics Quiz: Analyze Force Interactions Using Data

Practice Analyze Force Interactions Using Data in Physics with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

Question 1 / 18

0 of 18 answered

Based on the data shown, a block rests on a level surface while a spring scale measures the upward normal force FNF_NFN​. Using g=9.8 m/s2g = 9.8\ \text{m/s}^2g=9.8 m/s2, what is the block’s weight FgF_gFg​ (magnitude) for the 3.0 kg trial, and how does it compare to FNF_NFN​?

(Assume the block is not accelerating vertically.)

Select an answer to continue

What this quiz covers

This quiz focuses on Analyze Force Interactions Using Data, giving you a quick way to practice the rules, question types, and explanations that matter most for Physics.

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

Based on the data shown, a block rests on a level surface while a spring scale measures the upward normal force FNF_NFN​. Using g=9.8 m/s2g = 9.8\ \text{m/s}^2g=9.8 m/s2, what is the block’s weight FgF_gFg​ (magnitude) for the 3.0 kg trial, and how does it compare to FNF_NFN​?

(Assume the block is not accelerating vertically.)

  1. Fg=3.0 NF_g = 3.0\ \text{N}Fg​=3.0 N and it is less than FNF_NFN​.
  2. Fg=29.4 NF_g = 29.4\ \text{N}Fg​=29.4 N and it is approximately equal to FNF_NFN​. (correct answer)
  3. Fg=9.8 NF_g = 9.8\ \text{N}Fg​=9.8 N and it is greater than FNF_NFN​.
  4. Fg=32.4 NF_g = 32.4\ \text{N}Fg​=32.4 N and it is approximately equal to FNF_NFN​.

Explanation: This question tests understanding of applying Newton's Second Law to experimental data. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. For the 3.0 kg trial, the block's weight F_g = m g = 3.0 kg × 9.8 m/s² = 29.4 N downward, and since the block is at rest vertically, F_N balances it and is approximately equal. Choice B is correct because it accurately applies the weight calculation and recognizes the equilibrium with F_N. Choice A confuses mass and weight by using the mass value in kg where the force value in N is needed, forgetting to multiply by gravitational field strength (g = 9.8 m/s²). Net force determines acceleration: to find net force, identify all forces on ONE object, assign positive/negative signs based on direction, then add algebraically. Always verify units: forces in Newtons (N), masses in kilograms (kg), acceleration in m/s²—mixing these up is one of the most common errors.

Question 2

Based on the data shown, a 2.0 kg block is pulled to the right across a level surface. The applied force FappF_{app}Fapp​ and kinetic friction force FfF_fFf​ are measured each trial. If rightward is positive, what is the magnitude of the net force on the block in Trial 3? Use Fnet=Fapp−FfF_{net} = F_{app} - F_fFnet​=Fapp​−Ff​ (horizontal forces only).

  1. 1 N
  2. 3 N
  3. 5 N (correct answer)
  4. 11 N

Explanation: This question tests understanding of calculating net force from data. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. The data shows for Trial 3 that FappF_{app}Fapp​ is 8 N to the right and FfF_fFf​ is 3 N to the left, giving Fnet=8 N−3 N=5 NF_{net} = 8 \, \text{N} - 3 \, \text{N} = 5 \, \text{N}Fnet​=8N−3N=5N to the right. Choice C is correct because it properly sums the vector forces with correct signs, matching the magnitude of the net force. Choice D incorrectly adds forces that should be subtracted because the forces act in opposite directions, making the net force larger than it actually is. When analyzing force data, always check: (1) Are the units consistent? (2) If forces oppose each other, did I subtract rather than add? Quick check: Does your calculated force make physical sense? A net force of 5 N5 \, \text{N}5N on a 2 kg2 \, \text{kg}2kg block should produce about 2.5 m/s22.5 \, \text{m/s}^22.5m/s2 acceleration, which is reasonable for this setup.

Question 3

According to the table, two force sensors measure the tension at two points along the same light (approximately massless) rope while pulling a sled at constant speed. Which conclusion is best supported by the data?

Trial: 1, 2, 3, 4, 5 Tension near hand T1T_1T1​ (N): 25, 30, 35, 40, 45 Tension near sled T2T_2T2​ (N): 25, 30, 35, 40, 45

  1. The tension is the same throughout the rope in these trials. (correct answer)
  2. The tension near the sled must be larger than the tension near the hand.
  3. The rope tension is zero because the sled moves at constant speed.
  4. The data show Newton’s Third Law is violated because T1T_1T1​ and T2T_2T2​ are equal.

Explanation: This question tests understanding of identifying patterns in force measurements for tension in ropes. Newton's Third Law states that forces always occur in equal-magnitude, opposite-direction pairs acting on different objects—when object A exerts a force on object B, object B simultaneously exerts an equal force back on object A. Examining the data in the table, for each trial T_1 near the hand equals T_2 near the sled, such as 25 N for both in Trial 1, indicating uniform tension along the massless rope at constant speed. Choice A is correct because it recognizes the equal magnitudes in the data, consistent with tension being the same throughout an ideal rope. Choice B misapplies the concept by suggesting tension varies along the rope, when the data actually shows equality. When analyzing force data, always check: (1) Have I correctly applied F=ma with the right values? (2) Are the units consistent? (3) If forces oppose each other, did I subtract rather than add? Always verify units: forces in Newtons (N), masses in kilograms (kg), acceleration in m/s²—mixing these up is one of the most common errors.

Question 4

According to the table, the same horizontal net force is applied to carts of different mass on a low-friction track. Which statement best describes the relationship between mass and acceleration in the data?

Net force FnetF_{\text{net}}Fnet​ is approximately constant at 4.0 N.

Mass (kg): 0.50, 1.00, 1.50, 2.00, 2.50 Acceleration (m/s²): 8.0, 4.0, 2.7, 2.0, 1.6

  1. Acceleration is directly proportional to mass.
  2. Acceleration is approximately inversely proportional to mass. (correct answer)
  3. Acceleration is constant because the net force is constant.
  4. Mass and acceleration are unrelated because the values are not identical.

Explanation: This question tests understanding of interpreting force-mass-acceleration relationships from data. Newton's Second Law states that the net force on an object equals its mass times its acceleration (F = ma), meaning heavier objects require more force to achieve the same acceleration. Examining the data in the table, as mass increases from 0.50 kg to 2.50 kg, acceleration decreases from 8.0 m/s² to 1.6 m/s², and calculations like a = 4.0 N / 1.50 kg ≈ 2.7 m/s² confirm the inverse relationship. Choice B is correct because it accurately identifies the pattern of inverse proportionality between mass and acceleration for constant net force. Choice A reverses the cause-effect relationship, claiming acceleration increases with mass, when the data actually shows it decreases. In force data, look for patterns: does one variable increase when another increases (proportional)? Does one decrease when another increases (inverse)? Does something stay constant? Quick check: Does your calculated force make physical sense? A 2 kg object shouldn't have a net force of 200 N in a typical classroom scenario.

Question 5

Based on the data shown, a student pulls a 3.0 kg crate to the right across a rough floor. The applied force and kinetic friction force are measured for several trials. What is the net force magnitude on the crate in Trial 4?

(Forces are horizontal; take right as positive.)

Trial: 1, 2, 3, 4, 5 FappF_{\text{app}}Fapp​ (N): 18, 22, 26, 30, 34 FfF_fFf​ (N, left): 12, 12, 12, 12, 12

  1. 12 N
  2. 18 N (correct answer)
  3. 30 N
  4. 42 N

Explanation: This question tests understanding of calculating net force from data. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. The data shows the crate experiences F_app = 30 N to the right in Trial 4 and F_f = 12 N to the left, giving net force = 30 N - 12 N = 18 N to the right. Choice B is correct because it properly sums the vector forces with correct signs to find the net force of 18 N. Choice C incorrectly adds forces that should be subtracted because they act in opposite directions, making the net force larger than it actually is. When analyzing force data, always check: (1) Have I correctly applied F=ma with the right values? (2) Are the units consistent? (3) If forces oppose each other, did I subtract rather than add? Always verify units: forces in Newtons (N), masses in kilograms (kg), acceleration in m/s²—mixing these up is one of the most common errors.

Question 6

According to the table, two force sensors measure the horizontal interaction forces during a push between two carts (Cart A pushes Cart B). Positive values indicate forces to the right. Which choice best supports Newton’s Third Law for this interaction?

Table: Force sensor readings during the push

  • FA→BF_{A\to B}FA→B​ = force on B by A (N)
  • FB→AF_{B\to A}FB→A​ = force on A by B (N)

Time (s): 0.00, 0.10, 0.20, 0.30, 0.40 FA→BF_{A\to B}FA→B​ (N): +12, +18, +24, +18, +12 FB→AF_{B\to A}FB→A​ (N): −12, −18, −24, −18, −12

  1. Cart A experiences a larger force because it is doing the pushing.
  2. The forces form an action–reaction pair because they are equal in magnitude and opposite in direction at each time. (correct answer)
  3. Newton’s Third Law is violated because the forces change over time.
  4. The forces are an action–reaction pair only at t=0.20 st=0.20\ \text{s}t=0.20 s when the forces are largest.

Explanation: This question tests understanding of identifying patterns in force measurements using Newton's Third Law. Newton's Third Law states that forces always occur in equal-magnitude, opposite-direction pairs acting on different objects—when object A exerts a force on object B, object B simultaneously exerts an equal force back on object A. Examining the data in the table, at each time such as 0.00 s, F_{A→B} is +12 N while F_{B→A} is -12 N, and this pattern of equal magnitudes but opposite signs continues at every interval, indicating the forces are on different carts. Choice B is correct because it recognizes the equal magnitudes and opposite directions at each time, confirming an action-reaction pair. Choice C misapplies Newton's Third Law by suggesting it's violated because forces change over time, when actually the law holds instantaneously regardless of changes. For action-reaction pairs, remember the key identifier: equal magnitudes, opposite directions, on DIFFERENT objects—if the forces act on the same object, they're not an action-reaction pair. To identify action-reaction pairs in data: look for forces with equal magnitudes measured on different objects at the same time.

Question 7

Based on the data shown, a cart of mass 1.5 kg1.5\ \text{kg}1.5 kg experiences a constant tension force to the right and a constant friction force to the left. During which trial is the cart's acceleration magnitude greatest?

Use Fnet=FT−FfF_{\text{net}} = F_T - F_fFnet​=FT​−Ff​ and a=Fnet/ma = F_{\text{net}}/ma=Fnet​/m.

  1. Trial 1
  2. Trial 2
  3. Trial 3
  4. Trial 4 (correct answer)

Explanation: This question tests understanding of calculating acceleration from net force data using Newton's Second Law. Newton's Second Law states that the net force on an object equals its mass times its acceleration (F = ma), meaning we can find acceleration using a = F_net/m. Looking at the data for each trial, we first calculate net force using F_net = F_T - F_f (tension minus friction), then divide by the cart's mass of 1.5 kg to find acceleration: Trial 1 gives a_1 = (F_T1 - F_f1)/1.5, and similarly for other trials, with Trial 4 showing the largest net force and therefore the greatest acceleration magnitude. Choice D is correct because it identifies the trial where the difference between tension and friction forces is greatest, producing the maximum net force and thus the maximum acceleration. Choice A confuses force and acceleration, selecting the trial with the smallest forces rather than considering the net force that determines acceleration. When analyzing force data, always follow the two-step process: (1) Calculate net force by properly combining all forces with correct signs, (2) Apply F = ma to find acceleration. Quick check: larger net force always means larger acceleration for the same mass—if your answer doesn't follow this pattern, recalculate.

Question 8

Based on the data shown, a student pulled a block at constant speed on a level surface with a spring scale. If the block's acceleration is approximately 0 m/s20\ \text{m/s}^20 m/s2 in every trial, what is the best estimate of the coefficient of kinetic friction μk\mu_kμk​ between the block and the surface?

Assume g=9.8 m/s2g = 9.8\ \text{m/s}^2g=9.8 m/s2 and that the scale reading equals the kinetic friction force magnitude in each trial.

  1. μk≈0.10\mu_k \approx 0.10μk​≈0.10
  2. μk≈0.20\mu_k \approx 0.20μk​≈0.20 (correct answer)
  3. μk≈0.40\mu_k \approx 0.40μk​≈0.40
  4. μk≈0.80\mu_k \approx 0.80μk​≈0.80

Explanation: This question tests understanding of analyzing force data to determine the coefficient of kinetic friction from equilibrium conditions. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. Looking at the data, since the block moves at constant speed (acceleration = 0 m/s²), the net force must be zero, meaning the applied force equals the friction force: F_app = F_f = μ_k × N = μ_k × mg. For each trial, we can calculate μ_k = F_app/(mg), and averaging the results from multiple trials gives μ_k ≈ 0.20. Choice B is correct because it accurately calculates the coefficient of kinetic friction from the equilibrium condition where applied force equals friction force. Choice C uses the correct numbers but incorrectly doubles the coefficient, possibly by confusing static and kinetic friction or misapplying the friction formula. When analyzing force data, always check: (1) Have I correctly identified equilibrium conditions? (2) Are the units consistent? (3) Does the coefficient value make physical sense for typical materials? Always verify units: forces in Newtons (N), masses in kilograms (kg), and coefficients are dimensionless—mixing these up is one of the most common errors.

Question 9

The measurements indicate two students push on a box from opposite sides. Force sensor 1 measures the push to the right and sensor 2 measures the push to the left. Based on the data, during which time interval is the net horizontal force on the box closest to zero?

  1. 0 s
  2. 1 s
  3. 2 s (correct answer)
  4. 3 s

Explanation: This question tests understanding of identifying when net force equals zero from opposing force measurements. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. Examining the data at each time interval, we need to find when the rightward push (Force 1) and leftward push (Force 2) are most nearly equal in magnitude, since net force = Force 1 - Force 2, and net force is closest to zero when these forces balance. Choice C is correct because at t = 2 s, the two opposing forces have the most similar magnitudes, making their difference (net force) closest to zero compared to other time intervals. Choice A incorrectly selects the time when one force is at its minimum rather than when the two forces are most balanced. Net force determines acceleration: to find net force, identify all forces on ONE object, assign positive/negative signs based on direction, then add algebraically. Quick tip: when looking for zero net force with opposing forces, find where the force magnitudes are most equal—the closer the magnitudes, the closer the net force is to zero.

Question 10

Based on the data shown, a block (mass 3.0 kg) rests on a level table. The normal force FNF_NFN​ was measured with a scale for different added loads placed on top of the block. Using g=9.8 m/s2g=9.8\ \text{m/s}^2g=9.8 m/s2, what is the best estimate of the block’s weight FgF_gFg​ (not including any added load)?

  1. 3.0 N
  2. 9.8 N
  3. 29 N (correct answer)
  4. 98 N

Explanation: This question tests understanding of analyzing force data using Newton's Second Law and weight calculations. The weight of an object is the gravitational force on it, calculated as Fg = mg where m is mass and g is gravitational field strength (9.8 m/s²). Looking at the data, when there's no added load (0 kg), the normal force is 29 N, which equals the block's weight alone; this makes sense because Fg = mg = (3.0 kg)(9.8 m/s²) = 29.4 N ≈ 29 N. Choice C is correct because it recognizes that the normal force with zero added load represents just the block's weight, and the calculation using the given mass confirms this value. Choice B confuses the gravitational field strength (g = 9.8 m/s²) with the actual weight force, treating the acceleration value as if it were the force value in Newtons. When analyzing weight from normal force data, the normal force on a level surface with no other vertical forces equals the total weight—find the baseline reading before any loads are added. Always verify units: weight is a force measured in Newtons (N), not to be confused with mass in kilograms (kg) or gravitational acceleration in m/s².

Question 11

Based on the data shown, a 1.5 kg cart is pulled to the right by a string. The tension force FTF_TFT​ and the friction force FfF_fFf​ were measured. What is the cart’s acceleration magnitude in Trial 2?

  1. 0.67 m/s2^22
  2. 1.3 m/s2^22 (correct answer)
  3. 2.0 m/s2^22
  4. 3.0 m/s2^22

Explanation: This question tests understanding of calculating net force from data and applying Newton's Second Law. Newton's Second Law states that the net force on an object equals its mass times its acceleration (F = ma), meaning we can find acceleration by dividing net force by mass. Looking at the data for Trial 2, the tension force is +4.0 N (to the right) and the friction force is -2.0 N (to the left), giving net force = 4.0 N - 2.0 N = 2.0 N to the right; with mass = 1.5 kg, acceleration = F/m = 2.0 N / 1.5 kg = 1.33 m/s², which rounds to 1.3 m/s². Choice B is correct because it properly calculates the net force by subtracting opposing forces, then correctly applies F=ma rearranged as a=F/m to find the acceleration. Choice C uses the net force value (2.0 N) as if it were the acceleration (2.0 m/s²), forgetting to divide by the mass, which is a common error when working with F=ma relationships. Net force determines acceleration: to find net force, identify all forces on ONE object, assign positive/negative signs based on direction, then add algebraically. Always verify units: net force in Newtons divided by mass in kilograms gives acceleration in m/s²—keeping track of units helps catch calculation errors.

Question 12

Based on the data shown, two different blocks (A and B) are each pulled with the same applied force across the same surface. Friction forces are measured while they slide. Which conclusion is best supported by the measurements?

  1. Block B has a larger net force because it has a larger friction force.
  2. Block A has a larger net force because it has a smaller friction force. (correct answer)
  3. Both blocks have zero net force because the same applied force is used.
  4. The net force cannot be found unless the masses of the blocks are given.

Explanation: This question tests understanding of calculating net force from data. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. Looking at the data, both blocks experience the same applied force of 25 N, but Block A has friction F_f = 8 N while Block B has friction F_f = 12 N, giving net forces of: Block A: 25 N - 8 N = 17 N, Block B: 25 N - 12 N = 13 N. Choice B is correct because it recognizes that Block A has the larger net force (17 N vs 13 N) due to its smaller friction force, correctly applying the principle that net force equals applied force minus opposing friction. Choice A reverses the cause-effect relationship, claiming Block B has larger net force because it has larger friction, when actually larger friction reduces net force when the applied force is the same. When analyzing force data, always check: (1) Have I correctly identified which forces add and which subtract? (2) Does larger friction mean larger or smaller net force? (3) Are the forces on the same object? Remember that friction opposes motion, so larger friction means smaller net force when the driving force is constant—this is why objects with less friction accelerate more easily.

Question 13

Based on the data shown, a 2.0 kg2.0\,\text{kg}2.0kg block is pulled to the right on a level table. The applied force FappF_{app}Fapp​ is to the right and kinetic friction FfF_fFf​ is to the left. What is the magnitude of the net horizontal force on the block in Trial 4?

  1. 2 N
  2. 8 N (correct answer)
  3. 18 N
  4. 26 N

Explanation: This question tests understanding of calculating net force from data. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. Looking at the data for Trial 4, the block experiences an applied force F_app = 18 N to the right and kinetic friction F_f = 10 N to the left, giving net force = 18 N - 10 N = 8 N to the right. Choice B is correct because it properly sums the vector forces with correct signs, subtracting the leftward friction force from the rightward applied force to get the net force magnitude. Choice C incorrectly adds forces that should be subtracted because the forces act in opposite directions, making the net force larger than it actually is by calculating 18 N + 10 N = 28 N instead of 18 N - 10 N = 8 N. When analyzing force data, always check: (1) Have I identified all forces on the object? (2) Are the directions accounted for with proper signs? (3) If forces oppose each other, did I subtract rather than add? Quick check: Does your calculated net force make physical sense? An 8 N net force on a 2 kg block would produce an acceleration of 4 m/s², which is reasonable for a block being pulled on a table.

Question 14

According to the table, a box is pushed up a ramp at constant speed. The normal force FNF_NFN​ is measured for different ramp angles. Which conclusion is best supported by the data? (Weight is constant; only FNF_NFN​ changes with angle.)

  1. The normal force increases as the ramp angle increases.
  2. The normal force is constant because the box’s mass is constant.
  3. The normal force decreases as the ramp angle increases.
  4. The normal force equals the applied force at every angle.

Explanation: This question tests understanding of identifying patterns in force measurements for inclined planes. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. Examining the data in the table, as the ramp angle increases from 0° to 40°, the normal force decreases from 98 N to 75 N, which matches the relationship F_N = mg cosθ where cosθ decreases with larger angles. Choice C is correct because it correctly identifies the pattern of decreasing normal force with increasing angle. Choice A reverses the cause-effect relationship, claiming normal force increases with angle, when the data actually shows it decreases. In force data, look for patterns: does one variable increase when another increases (proportional)? Does one decrease when another increases (inverse)? Does something stay constant? Always verify units: forces in Newtons (N), masses in kilograms (kg), acceleration in m/s²—mixing these up is one of the most common errors.

Question 15

Based on the data shown, a block is on a 30∘30^\circ30∘ incline and is pulled up the slope at constant speed by a rope. The tension FTF_TFT​ acts up the slope and kinetic friction FfF_fFf​ acts down the slope. In Trial 2, what is the magnitude of the downslope component of weight, Fg,∥F_{g,\parallel}Fg,∥​, on the block? (Assume net force along the slope is zero.)

  1. 5 N
  2. 10 N
  3. 25 N
  4. 35 N (correct answer)

Explanation: This question tests understanding of analyzing force interactions using data for equilibrium conditions. When an object moves at constant speed, the net force is zero, meaning all forces balance—in this case, the tension up the slope must equal the sum of friction and the weight component down the slope. Looking at the data for Trial 2, the tension F_T = 45 N acts up the slope and friction F_f = 10 N acts down the slope; since the block moves at constant speed (net force = 0), we have F_T = F_f + F_{g,∥}, so 45 N = 10 N + F_{g,∥}, giving F_{g,∥} = 35 N. Choice D is correct because it recognizes that at constant speed, the upslope tension must balance both the friction force and the weight component down the slope, correctly calculating 45 N - 10 N = 35 N. Choice C uses the correct numbers but misapplies the equilibrium condition, appearing to subtract friction from tension incorrectly or confusing which forces act in which direction. Net force determines acceleration: for constant speed (zero acceleration), the net force must be zero, so identify all forces and set their sum to zero. To solve equilibrium problems with data: list all forces with their directions, apply the zero net force condition, and solve for the unknown force—always double-check that your answer makes physical sense given the scenario.

Question 16

Based on the data shown, a 2.0 kg2.0\,\text{kg}2.0kg block is pulled to the right across a level surface. The applied force FappF_{app}Fapp​ and kinetic friction force FfF_fFf​ were measured for five trials. Taking rightward as positive, what is the magnitude of the net force ∣Fnet∣|F_{net}|∣Fnet​∣ on the block in Trial 4?

Trial 4 measurements: Fapp=18 NF_{app}=18\,\text{N}Fapp​=18N (right), Ff=7 NF_f=7\,\text{N}Ff​=7N (left).

  1. 11 N11\,\text{N}11N (correct answer)
  2. 25 N25\,\text{N}25N
  3. 7 N7\,\text{N}7N
  4. 36 N36\,\text{N}36N

Explanation: This question tests understanding of calculating net force from data. Net force is the vector sum of all forces acting on an object and determines whether the object accelerates—zero net force means constant velocity, while non-zero net force produces acceleration in the direction of the net force. The data shows the block experiences F_app = 18 N to the right and F_f = 7 N to the left, giving net force = 18 N - 7 N = 11 N to the right, so the magnitude is 11 N. Choice A is correct because it properly sums the vector forces with correct signs. Choice D incorrectly adds forces that should be subtracted because the forces act in opposite directions, making the net force larger than it actually is. When analyzing force data, always check: (1) Have I correctly identified all forces on one object? (2) Are the units consistent? (3) If forces oppose each other, did I subtract rather than add? Always verify units: forces in Newtons (N), and ensure directions are accounted for with signs—mixing these up is one of the most common errors.

Question 17

Based on the data shown, a student measures the weight (gravitational force) of different objects using a spring scale. Using g=9.8 m/s2g = 9.8\ \text{m/s}^2g=9.8 m/s2, which object’s measured weight is most consistent with Fg=mgF_g = mgFg​=mg?

Object: A, B, C, D, E Mass (kg): 0.50, 1.20, 2.00, 3.50, 4.00 Measured weight FgF_gFg​ (N): 4.9, 10.0, 19.6, 30.0, 39.2

  1. Object B
  2. Object D
  3. Object A
  4. Object C (correct answer)

Explanation: This question tests understanding of analyzing force-mass relationships using data with F_g = mg. Newton's Second Law states that the net force on an object equals its mass times its acceleration (F = ma), meaning heavier objects require more force to achieve the same acceleration. Comparing the objects, for Object C with mass 2.00 kg, calculated F_g = 2.00 kg × 9.8 m/s² = 19.6 N, which exactly matches the measured 19.6 N, showing high consistency. Choice D is correct because it identifies Object C as having measured weight matching the prediction from F_g = mg. Choice B confuses mass and weight by selecting Object D where measured 30.0 N differs from 3.50 kg × 9.8 m/s² = 34.3 N, forgetting to check the multiplication. When analyzing force data, always check: (1) Have I correctly applied F=ma with the right values? (2) Are the units consistent? (3) If forces oppose each other, did I subtract rather than add? Quick check: Does your calculated force make physical sense? A 2 kg object shouldn't have a net force of 200 N in a typical classroom scenario.

Question 18

According to the table, a cart is pulled horizontally by a rope on a low-friction track. Using Newton’s Second Law (F=maF=maF=ma), what is the magnitude of the net force on the cart in Trial 3?

  1. 0.60 N
  2. 1.2 N
  3. 2.4 N (correct answer)
  4. 4.0 N

Explanation: This question tests understanding of analyzing force data using Newton's Second Law. Newton's Second Law states that the net force on an object equals its mass times its acceleration (F = ma), meaning heavier objects require more force to achieve the same acceleration. Looking at the data for Trial 3, the cart has a mass of 0.60 kg and acceleration of 4.0 m/s², so using F = ma gives F = (0.60 kg)(4.0 m/s²) = 2.4 N. Choice C is correct because it accurately applies F=ma to the given data, multiplying the mass and acceleration values from Trial 3 to find the net force. Choice B confuses mass and weight by using the mass value in kg where the force value in N is needed, appearing to multiply 0.60 by 2 instead of properly applying F = ma with the acceleration of 4.0 m/s². When analyzing force data, always verify that you're using the correct formula: F = ma requires mass (kg) times acceleration (m/s²) to get force (N). Always verify units: forces in Newtons (N), masses in kilograms (kg), acceleration in m/s²—mixing these up or forgetting to multiply is one of the most common errors in force calculations.