C.-2 miles per hour per second
Explanation;
Acceleration = change in velocity / time
Acceleration = (final velocity - initial velocity )/time
Acceleration = (v - u)/t
Given: u = 20 miles per hour, v = 10 miles per hour
t = 5 seconds
Acceleration = (10 - 20)/5
Acceleration = -10/5
Acceleration = -2 miles per hour per second
