An object moving at 32m/s takes 8s to come to a stop. What is the object's acceleration?

Acceleration = (change in speed) / (time for the change)

Change in speed = (speed at the end) - (speed at the beginning)

= 0 - 32 m/s = - 32 m/s.

Acceleration = (-32 m/s) / (8 s) = - 4 m/s²