Question regarding acceleration?

Question

A) is it possible for an object with zero speed to have a non-zero acceleration? explain please.

B) can a body moving at constant speed have a non-zero acceleration? explain also

Answer 1

Acceleration is the rate of change of velocity.  A ball thrown in the air is subject to acceleration due to gravity.  At the apex of its flight it will have zero speed and an acceleration of 9.8 m/s².

If the speed is constant, then the rate of change of speed is zero so the acceleration is zero.