Question

The velocity of a ball as it is thrown up is 20 meters/second. It attains zero velocity after 3.5 seconds. What is the average acceleration of the ball during its upward flight?

Answer 1

avg. acceleration = (vf - vi) / t
where vf is the final velocity, vi is the initial velocity, and t is the change in time

it says the ball ends at 0 velocity, so vf should be 0
vi is the initial velocity given to the ball by throwing it (20 m/s)
and t is given as 3.5

simple plug and chug from there