Question

The velocity of a particle is zero at t = 0.
(a) The acceleration at t = 0 must be zero.
(b) The acceleration at t = 0 may be zero.
(c) If the acceleration is zero from t = 0 to t = 10 s, the speed is also zero in this interval.
(d) If the speed is zero from t = 0 to t = 10 s the acceleration is also zero in this interval.

Answer 1

(b) The acceleration at t = 0 may be zero.
(c) If the acceleration is zero from t = 0 s to t = 10 s, the speed is also zero in this interval.
(d) If the speed is zero from t = 0 s to t = 10 s, the acceleration is also zero in this interval.
(b) Acceleration will be zero only when the change in velocity is zero.
(c) Since the acceleration is zero from t = 0 s to t = 10 s, change in velocity is 0.
Velocity in this interval = Initial velocity = 0
Also,
Speed in this interval = Initial speed = 0
(d) From t = 0 s to t = 10 s, speed is zero.
Here, velocity is zero and initial velocity is zero.
So, the change in velocity is zero; i.e., acceleration is zero.