Q18 of 42 Page 33

The position time graph of a body of mass 2 kg is as given in Fig. 5.4. What is the impulse on the body at t = 0 s and t = 4 s.

As we know impulse is change in momentum which can be written in terms of force

We have given mass of body m=2 kg, initial velocity (v1) at t=0 is zero. Now in the interval x-t graph is straight line that mean velocity of body will remain constant.


So v2


And when the slope of graph is zero so velocity will also be zero i.e. v3=0


Now or Impulse=change in momentum


Impulse at



Impulse at



So from above observation impulse at increased by and at it is decreased by .


More from this chapter

All 42 →
16

A girl riding a bicycle along a straight road with a speed of 5 m s-1 throws a stone of mass 0.5 kg which has a speed of 15 m s-1 with respect to the ground along her direction of motion. The mass of the girl and bicycle is 50 kg. Does the speed of the bicycle change after the stone is thrown? What is the change in speed, if so?

 17

A person of mass 50 kg stands on a weighing scale on a lift. If the lift is descending with a downward acceleration of 9 m s-2, what would be the reading of the weighing scale? (g = 10 m s-2)

 19

A person driving a car suddenly applies the brakes on seeing a child on the road ahead. If he is not wearing seat belt, he falls forward and hits his head against the steering wheel. Why?

 20

The velocity of a body of mass 2 kg as a function of t is given by v(t) = 2t î + t2 j. Find the momentum and the force acting on it, at time t= 2s.