Here's why:
* At maximum height, the object momentarily stops moving upwards. It's about to start falling back down.
* Velocity is a vector quantity, meaning it has both magnitude (speed) and direction. Since the object has stopped moving upwards, its velocity at that instant is zero.
Important Note: While the instantaneous velocity is zero at the maximum height, the object's acceleration due to gravity is still acting on it, pulling it downwards.
