(b) The acceleration at t = 0 may be zero.
(c) If the acceleration is zero from t = 0 to t - 10s speed is also zero in this interval.
(d) If the speed is zero from t = 0 to t =10s the acceleration is also zero in this interval.
Explanation:
(a) is not true. Consider the case of a particle dropped vertically downward, its velocity at t=0 is zero but acceleration is not zero.
(b) is true because we do not have information about the velocity in next instants. If in next instants the velocity still remains zero, the acceleration will be zero.
(c) is true because, if acceleration is zero that means there is no change in velocity. The velocity remains zero in this interval.
(d) is true because if the speed remains zero from t=0 to t= 10 s, that means the particle is at rest in this interval, so the acceleration is also zero in this interval.
