Zero velocity and zero acceleraton

[Throwback24]

If velocity is the change in position per unit time and acceleration measures the change in velocity of an object, can an object zero velocity or zero acceleration?

In terms of a baseball, the baseball stands still for a moment at the top. Would that mean it has zero velocity?

But does a baseball ever have zero acceleration? It doesn't speed up nor speed down at the at the arc, so would that be zero as well?

Thank you in advance.

 

[G01]

Is the baseball being thrown like projectile?

If it is thrown as a projectile it does always have a velocity, at least in the x direction.

In the y- direction it's y velocity is 0 at the highest point on the path, but the total velocity will still be non zero, unless it was thrown straight up.

Also, there is a constant nonzero force on the ball (gravity) at all times. What does this tell you about the acceleration of the ball at all times?

 

[curly_ebhc]

You are fairly close to understanding what is going on. If you throw the projectile straight up, it will have zero velocity at the top but the acceleration will always = 9.8 m/s/s downwards.

First it is only stationary (v=0) for a fraction of a fraction of a second.

Second it has an upwards velocity immediatly before and a downwards velocity immediatly afterwards. So it has to have a downwards acceleration.