Application of Second law of Motion

Q.

In high jump competition the athlete is made to fall on a cushioned bed to:

1. To decrease his momentum fast.

2. Make him sleep comfortably.

3. Make him stop quickly.

4. Increase the time to stop

Q.

A force of 50N produces an acceleration of 10m/s²on a body of mass m₁ and an acceleration of 20m/s² on a body of mass m_2. Find the acceleration produced by the same force if both the bodies were tied together.

Q.

A bus starts from the stop and take 50 second to get the speed of 10m/s. If the mass of the bus along with passengers is 10000 kg, calculate the force applied (in N) by the engine of bus to push the bus to the speed of 10m/s?

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Q.

Two cars having masses in the ratio 4:5, accelerate in the ratio 2:3. Find the ratio of forces exerted by each of them.

Q.

What force can change the velocity of a body of mass 1kg from 20 m/s to 30m/s in 2 seconds?

1. 25 N

2. 15 N

3. 10 N

4. 5 N

Q. A $10g$ bullet is fired from a gun with a velocity of $250m{s}^{-1}$. How much force is experienced by the gunman if it takes $0.1s$ to fire a shot?​

1. $25N$
2. $20N$
3. $23N$
4. $30N$

Q.

A force acts for 0.1 sec on a body of mass 2kg initially at rest. The force is then withdrawn and the body moves with a velocity of 2m/s . Find the magnitude of force

Q.

For system on which no net external force acts, momentum is:

1. Never zero

2. Not conserved

3. Conserved

4. Zero

Q.

A goalkeeper in a game of football pulls his hands backward after holding the ball shot at the goal. This enables the goalkeeper to

1. increase the rate of change of momentum

2. increase the inertia

3. exert a large force on the ball

4. reduce the force exerted by the ball on hands

Q.

Two balls at the same temperature collide. Which of the following gets conserved ?

1. velocity

2. temperature

3. Momentum

4. inertia

Q. When a body is acted upon by a constant net force, its velocity must be

1. zero
2. variable
3. constant

Q. A person fires a 30 g bullet towards the target in a shooting range with a velocity of 30 m/s. The bullet embeds into the target up to a depth of 10 cm before coming to a stop. What will be the magnitude of the force on the bullet?

1. 165 N
2. 200 N
3. 175 N
4. 135 N

Q.

A stone of 1 kg is thrown with a velocity of 20m/s across a frozen surface of a lake and comes to rest after travelling 50 m. What is the force of friction between the stone and the ice?

Q.

How much force will be applied on an object of mass25 kg to accelerate it to a value of 7 m/sec square .

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Q. a driver of a three wheeler moving with a speed of 36 km per hour sees a child standing in the middle of the road and bring his vehicle at rest in 0.4 seconds just in time to save the child.the average retarding force on the vehicle is ( the mass of the three wheeler is 400 kg and mass of the driver is 60 kg)

Q.

Question:

A bullet of mass of 10 gram travelling horizontally with a velocity of 150 m/s strikes a stationary wooden block and comes to rest in 0.03 s. Calculate the distance of pentration of the bullet into the block also calculate the magnitude of the force exerted by the wooden block on the bullet.

In the answer, how did the force have positive acceleration??

Explain briefly..

Q.

Write down three equations of motion.

Q. A lead bullet of mass $2kg$, travelling with a velocity of $20m{s}^{-1}$, comes to rest after penetrating $20m$ in a still target. Find the average acceleration $\left(a\right)$ of the bullet and resistive force $\left(F\right)$ applied by the target.

1. $a=40m{s}^{-2}$
   $F=80N$
2. $a=20m{s}^{-2}$​​
   $F=40N$
3. $a=-10m{s}^{-2}$
   $F=20N$
4. $a=0m{s}^{-2}$
   $F=0N$

Q.

A bus starts from the stop and take 50 second to get the speed of 10m/s. If the mass of the bus along with passengers is 10000 kg, calculate the force applied (in N) by the engine of bus to push the bus to the speed of 10m/s?

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Q.

A car of 1000 kg, is accelerating due to a net force 1200 N. If 4 people of mass 50 Kg board the car, then what is the new acceleration ? (in M/s²)

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Q.

A rope is stretched between two boats at rest. A sailor in the first boat pulls the rope with a constant force of 100 N. First boat with the sailor has a mass of 250 kg whereas the mass of second boat is double of this mass. If the initial distance between the boats was 30 m, the time taken for two boats to meet each other is (neglect water resistance between boats and water)

Q. A force act for 0.1 s on a body of mass of 2.0kg in Italy at rest . The force in then withdraw and the body moves with a velocity of 2ms-1 . Find the magnitude of force.

Q.

What is the net force acting on an object of mass $10kg$ moving with a uniform velocity of $10m{s}^{-1}$?

1. $10N$

2. $98N$

3. $0N$

4. $15N$

Q.

An object of mass m kg is travelling on a smooth straight road with a velocity of 54Kmph. It is stopped due to the application of brakes, which produces a uniform retardation, by exerting a constant resisting force F newton. The object covers a displacement of 56.25m. The numerical relation, between the force F and mass m will be:

1. F= 4m

2. F = 3m

3. F = ½m

4. F= 2m

Q. A body of mass $2kg$ having a velocity of $2m{s}^{-1}$ is brought to rest within a distance of $2m$. Find the magnitude of force acting on the body.

1. $8N$
2. $1N$
3. $4N$
4. $2N$

Q. find the magnitude of applied force that acts on a body of mass 10 kg for the duration of 5 second to increase its velocity 5 to 10 m/s. if the force is applied for 10 seconds then the find the final velocity of the object

Q. Suppose that a box is accelerating at a rate of $2m{s}^{-2}$. If the net force is tripled and the mass is doubled, then what is the new acceleration of the box?

1. $4m{s}^{-2}$
2. $6m{s}^{-2}$
3. $3m{s}^{-2}$
4. $2m{s}^{-2}$

Q.

Which would require a greater force ?

1. accelerating a 2 kg mass at 5 m/s²

2. accelerating a 1kg mass at 1

3. accelerating a 0.5 kg mass at 2

4. accelerating a 4 kg mass at 2

Q. Mass times the rate of change of velocity of an object is equal to:

1. Speed
2. Momentum
3. Force
4. Displacement

Q. According to Newton's Second low of Motion -

1. $f=m\times v$
2. $f=m\times a$
3. $f=\frac{m}{a}$
4. $f=\frac{m}{v}$