Question

Is it possible for an accelerating body to have zero velocity? Explain.

Answer 1

Hint: Acceleration is the rate of change of velocity. If it is not zero, this only means velocity is changing over time. It does not mean velocity cannot be zero at a particular time. It only means that velocity cannot remain zero.

Complete Step By Step answer:
Velocity is the rate of change of displacement of a body. Velocity is a vector quantity, meaning it has both magnitude as well as direction. For velocity to change either its magnitude or direction should (both can change too). Acceleration is the rate of velocity of a body.
$a=\dfrac{dv}{dt}$,
where a is acceleration, v is velocity and t is time.

If acceleration of a body is non-zero i.e. the body is accelerating, the change in velocity of the body cannot be zero i.e. $dv\ne 0$ ($dv$ is the change in velocity in $dt$ time). However, this does not mean that the velocity of a body cannot be zero. Velocity of the body at an instant can be zero for an accelerating body.
For example, when a ball is thrown up in air, at the topmost point velocity of the ball is zero because it is at rest but acceleration of the ball for the whole journey is non-zero and in this case constant too. What actually happens here is the downward acceleration decreases the upward velocity of the body makes it zero at the topmost point and then further changes the direction of velocity to vertically downward direction.

Note: The velocity of an accelerating body can be zero only for a specific instant. It cannot remain zero. It has to change, because the change in velocity i.e. $dv$ is non zero. The slope of the velocity-time graph at a point will give us acceleration of the body at that point.