Question

What happens to the acceleration when the velocity is zero

Answer 1

Answer:

It's easy to fall into the temptation to say that when the velocity is zero, then the acceleration is also zero. But wait! To answer this question we need to bring out the concept of instantaneous velocity. This type of velocity stands for a specific moment, a specific instant of time, that is, $t=1, \ t=2, \ t=3, \ t=3.2 \ t=4.5$. If so, then acceleration may not be zero when velocity is zero. For example, suppose you throw an object upward, when it is at the top of the travel the instantaneous velocity is zero because it changes from positive to negative value and there is a moment when it must be zero, but yet there is a constant acceleration by the Earth's gravity at that moment. Even though the velocity at that stationary moment is zero, it doesn't imply the acceleration must be zero, so it has a value and in this case is $-9.8m/s^{2}$