A car traveling at 24 m/s starts to decelerate steadily. It comes to a complete stop in 7 seconds. What is its acceleration?

Answer: - 3.43 m/s^2

Explanation:

1) Acceleration = [change in speed] / [time elpased]

2) Change in speed = final speed - initial speed

Since the car comes to a complete stop, the final speed is 0

3) time = 7 seconds

4) Calculation:

acceleration = [ 0 m/s - 24 m/s] / 7 s = - 24 m/s / 7 s = - 3.43 m/s/s or - 3.43 m/s^2

The negative sign means that the car decelerated.