Quiz Chapter 2: Force and Motion I

1. An object in free fall near Earth's surface accelerates at approximately 9.81 m s⁻². This means that during every second of fall:

1. Its displacement increases by 9.81 m
2. Its velocity increases by 9.81 m s⁻¹
3. Its mass decreases by 9.81 kg
4. Its weight increases by 9.81 N

2. A soccer player kicks a 0.5 kg stationary ball, giving it a speed of 20 m s⁻¹. If the foot stays in contact with the ball for 0.05 s, calculate the average force exerted on the ball.

1. 10 N
2. 100 N
3. 200 N
4. 400 N

3. Car bumpers and crumple zones are designed to collapse during a collision. How does this protect passengers?

1. By decreasing collision time to reduce force
2. By increasing collision time to reduce impulsive force
3. By eliminating momentum completely before impact
4. By increasing vehicle acceleration during impact

4. In an elastic collision between two objects, which of the following quantities are conserved?

1. Total momentum only
2. Total kinetic energy only
3. Both total momentum and total kinetic energy
4. Neither momentum nor kinetic energy

5. Which of the following actions increases the impulsive force in an activity?

1. Bending knees upon landing after a high jump
2. Using thick mattresses in pole vaulting
3. Using a hard wooden bat instead of a soft rubber bat to hit a baseball
4. Wearing seatbelts with stretchable fabric

6. Calculate the weight of an astronaut of mass 70 kg on the Moon, where gravitational field strength g = 1.6 m s⁻².

1. 112 N
2. 43.75 N
3. 686 N
4. 700 N

7. A trolley of mass 2 kg moving at 4 m s⁻¹ collides and sticks to a stationary trolley of mass 2 kg. Find their common velocity after collision.

1. 1.0 m s⁻¹
2. 2.0 m s⁻¹
3. 4.0 m s⁻¹
4. 8.0 m s⁻¹

8. If a feather and a heavy steel ball are dropped simultaneously from the same height in a vacuum, which statement is true?

1. The steel ball hits the ground first because it has greater mass
2. The feather hits the ground first because air resistance is zero
3. Both hit the ground at the same time because both experience the same gravitational acceleration
4. Both remain suspended because there is no air pressure

9. A stone is thrown vertically upwards with an initial velocity of 15 m s⁻¹. Assuming g = 9.81 m s⁻² and neglecting air resistance, what is its velocity at the maximum height?

1. 15.0 m s⁻¹
2. 9.81 m s⁻¹
3. 0 m s⁻¹
4. -15.0 m s⁻¹

10. What is the momentum of a 1200 kg car traveling at a constant velocity of 15 m s⁻¹?

1. 80 kg m s⁻¹
2. 1800 kg m s⁻¹
3. 18000 kg m s⁻¹
4. 27000 kg m s⁻¹