Answer: - 3.43 m/s^2
Step-by-step 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.