English Medium इयत्ता ९ - CBSE Question Bank Solutions

A 150 g ball, travelling at 30 m/s, strikes the palm of a player’s hand and is stopped in 0.05 second. Find the force exerted by the ball on the hand.

State the law of conservation of momentum.

Discuss the conservation of momentum in each of the following cases :
(i) a rocket taking off from ground.
(ii) flying of a jet aeroplane.

An unloaded truck weighing 2000 kg has a maximum acceleration of 0.5 m/s². What is the maximum acceleration when it is carrying a load of 2000 kg ?

Why are car seat-belts designed to stretch some what in a collision ?

The troops (soldiers) equipped to be dropped by parachutes from an aircraft are called paratroopers. Why do paratroopers roll on landing ?

Why would an aircraft be unable to fly on the moon ?

Explain why it is possible for a small animal to fall from a considerable height without any injury being caused when it reaches the ground.

A boy of mass 50 kg running at 5 m/s jumps on to a 20 kg trolley travelling in the same direction at 1.5 m/s. What is their common velocity ?

A girl of mass 50 kg jumps out of a rowing boat of mass 300 kg on to the bank, with a horizontal velocity of 3 m/s. With what velocity does the boat begin to move backwards ?

A truck of mass 500 kg moving at 4 m/s collides with another truck of mass 1500 kg moving in the same direction at 2 m/s. What is their common velocity just after the collision if they move off together ?

A ball X of mass 1 kg travelling at 2 m/s has a head-on collision with an identical ball Y at rest. X stops and Y moves off. Calculate the velocity of Y after the collision.

A heavy car A of mass 2000 kg travelling at 10 m/s has a head-on collision with a sports car B of mass 500 kg. If both cars stop dead on colliding, what was the velocity of car B ?

A man wearing a bullet-proof vest stands still on roller skates. The total mass is 80 kg. A bullet of mass 20 grams is fired at 400 m/s. It is stopped by the vest and falls to the ground. What is then the velocity of the man?

Explain why do spinach look green, papaya yellow and edible part of water melon red?

Define the following term: 

Protoplasm

List one function of the Following:

Osteoblast

List One Function of the Following:

Chondroblasts

What is the function of bone?

Name the following :

(a) Tissue which stores fat