Question # 01

Why do we wear seat belt?

Answer:

When a moving car stops quickly,the passengers move forward towards the windshield. Seat belts changes the forces of motion and prevent the passengers from moving. So, the chance of injury reduced.

Question # 02

Why do we wear helmet?

Answer:

Helmet is padded to extend the time of any collision and we prevent serious injuries. 

Question # 03

Do objects of different weights fall with the same acceleration on the earth?

Answer:

Yes, when the air friction is negligible, then the objects fall with the same  acceleration on the earth, having different weights.

Question # 04

How the displacement of a vertically thrown ball varies with time.

Answer:

The vertical displacement increases with time. When it gets maximum displacement d(m), then vertical velocity becomes zero. Now, the ball starts moving downward, the vertical displacement decreases and velocity increases with time.

Question # 05

A car accelerates along a road which force actually moves the car?

Answer:

Since the engine only rotates the wheels of car. The force of friction between the tires and road accelerates the car.

Question # 06

Either rubber bullet or lead bullet be more effective in knocking a bear down?

Answer:

In case of rubber bullet, the time of collision is greater and impulsive force is smaller. But in case of lead bullet, the time of collision is smaller and impulsive force is greater. So, lead bullet is effect to knocking down.

Question # 07

Does a moving object have impulse?

Answer:

A moving object may or may not have impulse. If it move with uniform velocity, it has no impulse. If it move with variable velocity, it has impulse.

Question # 08

Why greater force is necessary to fracture skull with hair than the naked skull>

Answer:

In case of skull with hair, the time of collision is greater and impulsive force is smaller, So, we required very large force to fracture the skull with hair.

Question # 09

What is the effect on the speed of a fighter plane chasing another when it opens fire? What happens to the speed of pursued plane when it returns the fire?

Answer:

When the fighter plane opens the fire, its momentum will be in backward direction and its speed decreases.When pursued plan opens fire in backward direction.then the momentum of plane will be in forward direction and its speed increases.

Question # 10

What is the physical significance of momentum?

Answer:

It represents the quantity of motion in the moving body.

Question # 11

A meteor when enters into earths atmosphere it burns. What happens to its energy and momentum?

Answer:

The energy pf the meteor is converted into heat energy and momentum is transferred to the particles in the atmosphere.

 Question # 12:

A man sitting in a bus moving with constant acceleration throw a ball straight up in the air. Where does the ball fall?

Answer:

Since, there is the acceleration so velocity changes in every second. So it falls behind the man.

Question # 13:

Why does a cricket player reface his hands backward while catching?

Answer:

This is done to decrease the time of collision, so impulsive force decreases on the hand.

Question # 15:

How horizontal component of velocity behaves in the projectile motion?

Answer:

In the projectile motion, the horizontal component of velocity remains constant.

Question # 16:

How vertical component of velocity behaves in the projectile motion?

Answer:

In projectile motion, the vertical component of velocity varies point to point.

Question # 17:

During what motion velocity becomes perpendicular to acceleration?

Answer:

If a body moves with uniform speed in a circle, then the acceleration is perpendicular to velocity.

Question # 18:

A bomber drops a bomb when it is vertically above the target, it misses it. Explain why.

Answer: 

Because its trajectory is parabolic and its motion is not vertically free fall.

Question # 19:

You are travelling in  bus moving with constant velocity. You throw a ball straight upwards will it land in front of you, behind you or in your lap?

Answer:

Since, the ball moves with uniform velocity, so there is no change in the velocity of bus. Therefore, a ball will land in your lap.