Question

According to Newton’s law of motion rate of change of momentum is directly proportional to applied force.

a. Impulse has the unit similar to that of 

1. Momentum

2. force

3. time

4. Energy

b. A man falling from certain height receives more injuries when he falls on a marble floor than when he falls on a heap of sand. Explain. Why?

c.

Force – time graph for a body starting from rest is shown in the figure. What is the velocity of the body at the end of 12 second? (Mass of the body is 5 kg).

Answer 1

a. 1. Momentum.

b. When a man falls on a marble floor, the momentum is reduced to zero in lesser time. Due to this, the rate of change of momentum is large. So greater force acts on a man falls on marble floor.

c. The area of force – time graph gives change in momentum.

ie. change in momentum,

mv = 1/2 × (12 – 4) × (20 -10)

mv = 40