Fig. shows the position-time graph of a particle of mass 4 kg. What is the (i) force acting on the particle for `t lt 0, t lt 4 s, 0 lt t lt 4 s`? (ii) impulse at t = 0 and t = 4 s? Assume that the motion is one dimensional.

Explanation

For `t lt 0.` No force as Particles is at rest.
For `t gt 4s`, No force again particle comes at rest.
For `0 lt t lt 4s,` as slope of OA is constant so velocity constant i.e., a =0, so force must be zero.
(b) Impulse at t= 0
Impulse =change in momentum
`I=m(v-u)=4 (0-0.75)=3"kg ms"^(-1)`
Impulse at t=4s
`I=m(v-u) =4(0.075)=-3kg ms^(-1)`