A car moving at 20 m s^-1 begins decelerating at 2 m s^-2 when 96 m away from a wall. What is its speed when it reaches the wall?

1. Step: v^2 = 20^2 – 2 * 2 * 96 = 400 – 384 = 16. 2. Step: v = sqrt(16) = 4 m s^-1.