The displacement (x) of a particle depends on time (t) as x = αt2 - βt 3.
(a) The particle will return to its starting point after time α/β.
(b) The particle will come to rest after time 2α/3β.
(c) The initial velocity of the particle was zero but its initial acceleration was not zero.
(d) No net force will act on the particle at t = α/3β
