Read each statement below carefully and state with reasons and examples, if it is true or false ,
A particle in one-dimensional motion
(a) with zero speed at an instant may have non-zero acceleration at that instant
(b) with zero speed may have non-zero velocity,
(c) with constant speed must have zero acceleration,
(d) with positive value of acceleration must be speeding up.

Explanation

(a) True,, (b) False, (c) True (if the particle rebounds instantly with the same speed, it implies infinite acceleration which is unphysical), (d) False (true only when the chosen positive direction is along the direction of motion)