Acceleration time graph is shown in the figure for a particle moving along a straight line. The particle is initially at rest. Find the time instants when the particle comes to rest?

Particle comes to rest when sum of area under a – t curve is zero which happens at t = 0, 2, 4

Area under vt graph gives change in velocity

Area above time axis is taken as positive and area below time axis is negative.

At time t=0,2,4 .. the change in velocity is zero.