A man is standing on a spring platform. The reading of the spring balance is \(60\ \text{kg-wt}\). If a man jumps off the platform, then the reading of the spring balance:

1. first increases, then decreases to zero.

2. decreases.

3. increases.

4. remains the same.

A body of mass \(5\ \text{kg}\) is suspended by a spring balance on a smooth inclined plane as shown in the figure. The spring balance measures:

1. \(50\ \text{N}\)
2. \(25\ \text{N}\)
3. \(500\ \text{N}\)
4. \(10\ \text{N}\)

A lift is going up. The total mass of the lift and the passenger is \(1500\) kg. The lift's speed varies as shown in the graph. The tension in the rope pulling the lift at \(t=11^{\text{th}}\) s will be:

      
1. \(17400\) N
2. \(14700\) N
3. \(12000\) N
4. Zero

A player caught a cricket ball of mass \(150\ \text{g}\) moving at a rate of \(20\ \text{m/s}\). If the catching process is completed in \(0.1\ \text{s}\), then the force of the blow exerted by the ball on the hands of the player is:

1. \(0.3\ \text{N}\)
2. \(30\ \text{N}\)
3. \(300\ \text{N}\)
4. \(3000\ \text{N}\)

A rocket of mass \(100\ \text{kg}\) ejects exhaust gases at a rate of \(1\ \text{kg/s}\) with a velocity of \(500\ \text{m/s}\) relative to the rocket. Neglecting external forces, the initial thrust produced by the rocket is:

1. Zero
2. \(500\ \text{N}\)
3. \(1000\ \text{N}\)
4. \(2000\ \text{N}\)

In which of the following cases will a force not be required to keep the particle in the given motion?
(A) The particle is going in a circle.
(B) The particle is moving in uniform straight-line motion.
(C) The momentum of the particle is constant.
(D) The acceleration of the particle is constant.

Choose the correct option from the given ones:
1. (A) and (B)
2. (A) and (D)
3. (B) and (C)
4. (C) and (D)

A ball of mass \(150\ \text{g}\) starts moving with an acceleration of \(20\ \text{m/s}^2\) when hit by a force, which acts on it for \(0.1\ \text{s}\). The impulsive force is:

1. \(0.5\ \text{N-s}\)
2. \(0.1\ \text{N-s}\)
3. \(0.3\ \text{N-s}\)
4. \(1.2\ \text{N-s}\)

A body of constant mass has constant linear momentum. Which of the following quantities must remain constant? 

1. force.

2. velocity.

3. acceleration.

4. All of these

Rocket engines lift a rocket from the Earth's surface because hot gases with high velocity:

1. push against the Earth.

2. push against the air.

3. react against the rocket and push it up.

4. heat up the air, which lifts the rocket.

A force of \(50\) dynes is applied to a body of mass \(5\ \text{g}\), which is at rest for an interval of \(3\) seconds; then the impulse is: 

1. \(0 .15 × 10^{-3}  \ \text{Ns}\)
2. \(0 .98 × 10^{-3}\ \text{N s}\)
3. \(1.5 × 10^{-3}\ \text{N s}\)$\mathrm{}$
4. \(2.5 × 10^{-3}\ \text{N s}\)$\mathrm{}$