Question

Suppose that you toss a rock upward so that it rises and then falls back to the earth. If the acceleration due to gravity is 9.8 m/sec2, what is the rock’s acceleration at the instant that it reaches the top of its trajectory (where its velocity is momentarily zero)? Assume that air resistance is negligible.

Answer 1

The Rock's acceleration is 9.8 m/s^2 from the moment it leaves your hand until the moment it hits the ground. Its acceleration never changes. That's the acceleration of gravity as long as nothing is pushing the rock or holding it back.