Question

if velocity is zero is acceleration constant?

Answer 1

Well, acceleration tells us how the velocity changes with time as you can note it's also a vector quantity as velocity. If the velocity is constant you have no acceleration, I think maybe for now if you don't have calculus this definition will be ok: \[a = \frac{ \Delta v }{ \Delta t }\] this is average acceleration though you should look into instantaneous as well as I think that will answer your question.

But to answer your question, that's not specifically true, you can imagine a projectile motion/ ball being thrown into the air you have a constant acceleration due to gravity while the velocity is 0. Hopefully this makes some sense.

Answer 2

usually if velocity is zero acc. is zero as u can see from the above equation..but in some cases like in a projectile motion...velocity is zero at the highest point but acceleration (here g) is constant..

Answer 3

If velocity is zero OVER A PERIOD OF TIME, then acceleration is zero too.
If INSTANT velocity has a value equal to zero, acceleration can be anything.

Answer 4

Exactly I agree with all 3 of them
Acceleration is the rate of change of velocity, so if the velocity is zero there is no change thus the rate of change of it is zero, making the acceleration to be zero.
Go by the definitions then it is much easier :)