Answer:
Zero.
Explanation:
Given that a rock is thrown vertically upward at an initial velocity of 70 m/s. What is the approximate acceleration of the rock when it reaches its maximum height
(assume upward is the positive y direction)?
Since the reached the maximum height, the final velocity V will be equal to zero.
Using the first equation of motion to find the time.
And since it is a vertical direction, and not horizontal, the acceleration a will be equal to zero.