A tennis ball with a velocity of 7.97 m/s to the right is thrown perpendicularly at a wall. After striking the wall, the ball rebounds in the opposite direction with a velocity of −5.07 m/s to the left. If the ball is in contact with the wall for 0.011 s, what is the average acceleration of the ball while it is in contact with the wall? Answer in units of m/s^2.
The one that I assumed was the right equation was
(ωf=final velocity) (ωi=initial velocity) (α=acceleration) (Δt =change in time)
The Attempt at a Solution
I just plugged the numbers into the formula and solved for α, but the answer was wrong. What I am I doing incorrectly?