Question 1

Calvin is helping Joe to walk up a steep slope using a rope. Which of the following correctly shows the force Calvin and Joe exerts on the rope?

Accepted Answer

1. Calvin: Pull, Joe: Pull. Both Calvin (at the top) and Joe (at the bottom) must pull on the rope. Calvin pulls the rope up the slope to help Joe ascend, while Joe pulls the rope to brace himself and climb. Ropes can only exert pulling forces (they cannot push).

Question 2

Lindsey rolled an iron ball towards the wall. Which is/are the possible effect(s) of forces on the ball? A. The ball changes direction after hitting the wall. B. The ball becomes heavier. C. The ball moves more slowly towards position A after hitting the wall. D. The ball changes its shape.

Accepted Answer

2. A and C only. Forces can change the direction of a moving object (A — ball bounces off wall and changes direction) and can change the speed of an object (C — ball slows down after impact due to forces). Forces cannot change mass (B is wrong), and the iron ball is rigid so its shape won't change visibly (D is wrong).

Question 3

Four magnets, A, B, C and D, were hung from a ceiling. The magnets were of the same size. The diagram shows the number of steel pins each magnet attracts. Which one of the magnets is the weakest?

Accepted Answer

4. D. The strength of a magnet is shown by the number of steel pins it can attract. Magnet D attracts the fewest steel pins (only one), so it is the weakest magnet.

Question 4

Shawn placed four balls, P, Q, R and S, of similar sizes but different masses at different heights above a tray of sand. He predicted that the higher the ball is placed above the tray of sand, the deeper depression it will make. Which two balls should he use to test his prediction?

Accepted Answer

2. P and R. To test the prediction about height, only the height should change while mass is kept constant (fair test). P (40g, low) and R (40g, high) have the same mass but different heights, making them the correct pair.

Question 5

The diagram shows how energy can be converted from one form to another. Which of the following best represent activities P, Q, R and S?

Accepted Answer

1. P: Using ceiling fan, Q: Using wind turbine, R: Using an electric toaster, S: Sudden braking of a car. P (Electrical → Kinetic): a ceiling fan converts electrical energy to kinetic energy. Q (Kinetic → Electrical): a wind turbine converts kinetic energy of wind to electrical energy. R (Electrical → Heat): an electric toaster converts electrical to heat. S (Kinetic → Heat): sudden braking of a car converts kinetic energy to heat via friction. Option (1) matches all four correctly.

Question 6

Roshan pushed a toy, which was attached to a spring. He closed the lid as shown in Diagram 1. When he opened the lid, the toy jumped up as shown in Diagram 2. Which of the following would make the toy jump higher?

Accepted Answer

2. Use a lighter toy.. The elastic potential energy stored in the spring is converted to kinetic energy of the toy. A lighter toy needs less energy to gain the same height, so it will jump higher with the same spring. The lid is no longer in the way, the cup doesn't move, and a lighter spring would store less elastic energy.

Question 7

Landy placed a ladder against a wall. Which pair of forces helps to prevent the ladder from sliding off the wall?

Accepted Answer

4. B and D. To prevent the ladder from sliding, frictional forces must act on it. Force B (friction between wall and ladder, acting upward) prevents the ladder from sliding down the wall, and force D (friction between ground and ladder base, acting toward the wall) prevents the base from sliding outward. Together B and D keep the ladder in place.

Question 8

Vinod attached a strong magnet to a spring and placed it at the bottom of a ramp. He placed a copper coin at the top of the ramp and observed that it slid towards the magnet. What were the forces acting on the copper coin as it moved along the surface of the ramp? A. frictional force B. magnetic force C. gravitational force D. elastic spring force

Accepted Answer

3. A, B and C only. Copper is not a magnetic material, so it is NOT attracted by the magnet. However, the coin is on a ramp surface (frictional force A acts), gravity pulls it down the slope (gravitational force C), and although the question states it slides toward the magnet, this is due to gravity along the inclined surface — wait: the question states the coin slides towards the magnet, suggesting magnetic attraction. Since copper is non-magnetic, only friction (A) and gravity (C) act on it. The spring is attached to the magnet, not the coin, so D does not apply. B does not apply because copper is non-magnetic.

Question 9

Alexis threw a ball into the net as shown. Which of the following correctly shows the change in kinetic energy as the ball travels from R to T and from U to V?

Accepted Answer

3. R to T: Decreases, U to V: Increases. From R to T (ball rising to highest point T), kinetic energy decreases as it converts into gravitational potential energy and the ball slows down. From U to V (ball falling from hoop to ground), gravitational potential energy converts into kinetic energy and the ball speeds up — kinetic energy increases.

Question 10

Tate raised end G of a plank slightly as shown in Figure 1 but wooden block H did not slide down. When end G was raised high enough, Tate observed wooden block H sliding down as shown in Figure 2. [Figure 1: plank tilted slightly, block H stays still. Figure 2: plank tilted more, block H sliding down.] Tate repeated the experiment with three identical planks of different surfaces and raised end G until the wooden block H slide down as shown. [Figures: Surface X — plank raised at a steep angle for block to slide; Surface Y — plank only slightly raised (nearly flat) for block to slide; Surface Z — plank raised at moderate angle for block to slide.] Which of the following correctly shows the amount of frictional force between wooden block H and the surface?

Accepted Answer

2. Most friction: X, middle: Z, Least friction: Y. A steeper slope is needed to overcome more friction. Surface X requires the steepest angle, so it has the most friction. Surface Y requires only a slight tilt, so it has the least friction. Surface Z requires moderate tilt, so it's in the middle. Order: X (most) → Z (middle) → Y (least).

Question 11

A ball was released at point W. It rolled along the set-up as shown. Comparing the potential energy (PE) and kinetic energy (KE) of the toy as it moves from W to X, which one of the following graphs is correct? [Graphs: (1) KE rises from 0 to high while PE falls from high to 0 (crossing). (2) Both KE and PE decreasing in parallel from high to 0. (3) KE flat (constant horizontal line) while PE decreases. (4) KE decreases from high to 0 while PE increases from 0 to high.]

Accepted Answer

1. KE increases linearly from 0 to maximum while PE decreases linearly from maximum to 0 (they cross).. As the ball rolls from W (top) to X (bottom), gravitational potential energy decreases (height decreases) and is converted into kinetic energy, which increases as the ball speeds up. Graph (1) correctly shows KE increasing and PE decreasing with the lines crossing.

Question 12

Three similar wind turbines X, Y and Z were placed at different locations A, B and C as shown below. The amount of electrical energy generated by each wind turbine was measured and recorded in a graph below. [Graph: X has the steepest line (most energy produced over time), Y has a moderate slope, Z has the flattest line (least energy produced).] Based on the results in the graph, which of the following most likely represents the locations of the windmills X, Y and Z?

Accepted Answer

3. X: A, Y: B, Z: C. Wind turbines generate more electrical energy when wind speed is higher. Location A (on the hilltop) has the most exposure to wind → most energy → X. Location B (forested area) has trees that partially block wind → moderate energy → Y. Location C (among high-rise buildings) has the most wind blockage → least energy → Z. So X=A, Y=B, Z=C.

Question 13

The diagram below shows the path of a ball when it was thrown onto a trampoline. Points A, B, C and D are the different positions along the path travelled by the ball. Which of the following graphs shows how the amount of gravitational force acting on the ball changes as it travels from A to D?

Accepted Answer

4. Gravitational force is constant (horizontal line) throughout A to D.. Gravitational force depends on the mass of the ball and the gravitational pull of the Earth, both of which do not change during the ball's flight. Therefore, the gravitational force acting on the ball remains constant throughout its journey from A to D, represented by the horizontal line graph (4).

P6 Science CA1 2025 — Singapore Chinese Girls

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