NEET Physics: Physics - Mechanics questions with solutions

Q1. What bring the rolling ball to rest?

1. Force of friction
2. Gravitational force
3. Air drag
4. Buoyant force

Answer: Force of friction

The force of friction opposes the ball’s motion as it rolls along a surface, gradually reducing its speed until it stops. Gravity, buoyancy, and air drag may act in some situations, but friction is the main force that brings a rolling ball to rest on a surface.

Q2. A block of mass' \( m^{\prime} \) is kept on the ground as shown in figure. Which of the following statements is/are correct of action-reaction force pair? This question has multiple correct options

1. Normal force can never be a reactive force
2. Weight of the body is not a part of action reaction pair
3. Forces act on different bodies
4. None of these

Answer: Forces act on different bodies

An action-reaction pair always consists of equal and opposite forces acting on two different bodies. The weight of the block is the Earth’s pull on the block, and its reaction is the block’s pull on the Earth, so the pair does not act on the same body.

Q3. The weight of 50 kg person at the surface of earth is

1. \( 50 N \)
2. \( 35 N \)
3. \( 380 N \)
4. \( 490 N \)

Answer: \( 490 N \)

Weight is the gravitational force on a mass, given by W = mg. For a 50 kg person on Earth, W = 50 × 9.8 = 490 N, so the correct choice is D.

Q4. The magnitude of non-contact force depends upon:

1. Distance between two bodies
2. Mass of the two bodies
3. chemical properties of the two bodies
4. All of the above

Answer: Distance between two bodies

Non-contact forces like gravitational, electrostatic, and magnetic forces generally weaken or strengthen as the distance between objects changes. Their magnitude is not determined by chemical properties, and mass is only relevant for certain forces, not all non-contact forces.

Q5. In the figure shown, the plastic region occurs

1. Before point \( A \)
2. Beyond point A
3. Between points A and
4. Between points D and E

Answer: Beyond point A

Plastic deformation starts once the stress exceeds the yield point, where unloading would no longer return the material to its original shape. In the figure, that transition occurs beyond point A.

Q6. Which of the following are the examples of atmospheric pressure?

1. Fountain bottle
2. Ping pong funnel
3. Million dollar bet
4. All of the above

Answer: All of the above

Each listed example can be explained by atmospheric pressure acting on a surface or creating a pressure difference. Since fountain bottles, the ping pong funnel effect, and the million-dollar bet all involve this principle, the correct choice is all of them.

Q7. is applied to unwind a screw.

1. single force
2. Couple
3. Parallel force
4. None of these

Answer: Couple

A screw is unwound by applying a turning moment without pushing it sideways. A couple produces pure rotation, which is exactly what is needed.