English Medium कक्षा ९ - CBSE Question Bank Solutions

Explain how, a karate player can break a pile of tiles with a single blow of his hand.

Calculate the momentum of a toy car of mass 200 g moving with a speed of 5 m/s.

What is the change in momentum of a car weighing 1500 kg when its speed increases from 36 km/h to 72 km/h uniformly ?

What is the momentum in kg.m/s of a 10 kg car travelling at (a) 5 m/s (b) 20 cm/s, and (c) 36 km/h ?

Define momentum of a body. On what factors does the momentum of a body depend ?

Calculate the change in momentum of a body weighing 5 kg when its velocity decreases from 20 m/s to 0.20 m/s.

A plastic ball and a clay ball of equal masses, travelling in the same direction with equal speeds, strike against a vertical wall. From which ball does the wall receive a greater amount of momentum ?

A man throws a ball weighing 500 g vertically upwards with a speed of 10 m/s.

1. What will be its initial momentum ?
2. What would be its momentum at the highest point of its flight ?

Which physical quantity corresponds to the rate of change of momentum ?

State the relation between the momentum of a body and the force acting on it.

Which physical principle is involved in the working of a jet aeroplane ?

Name the principle on which a rocket works.

Fill in the following blanks with suitable words :

 Momentum is a _____________ quantity. Its unit is _____________.

Fill in the following blanks with suitable words :
In collisions and explosions, the total _____________ remains constant, provided that no external _____________ acts.

A 10 g bullet travelling at 200 m/s strikes and remains embedded in a 2 kg target which is originally at rest but free to move. At what speed does the target move off ?

A body of mass 2 kg is at rest. What should be the magnitude of force which will make the body move with a speed of 30 m/s at the end of 1 s ?

The velocity of a body of mass 10 kg increases from 4 m/s to 8 m/s when a force acts on it for 2 s.
(a) What is the momentum before the force acts ?
(b) What is the momentum after the force acts ?
(c) What is the gain in momentum per second ?
(d) What is the value of the force ?

A gun of mass 3 kg fires a bullet of mass 30 g. The bullet takes 0.003 s to move through the barrel of the gun and acquires a velocity of 100 m/s. Calculate:

1. the velocity with which the gin recoils.
2. the force exerted on gunman due to recoil of the gun

Name the law involved in the following situation :

the sum of products of masses and velocities of two moving bodies before and after their collision remains the same.

Explain why, a cricket player moves his hands backwards while catching a fast cricket ball.