The position x of a particle varies with time (t) as x = a t2 - b t3 . The acceleration at time t of the particle will be equal to zero
2a3b
ab
a3b
zero
Given that x=at2−bt3∴ velocity =dxdt=2at−3bt2and acceleration =ddtdxdt=2a−6bt∴t=2a6b=a3b