What is the acceleration of a car running at a constant speed of V = 10 m / s when the engine is turned off at the end of the second second second and the average speed is 9 m / s in the third second?

What is the acceleration of a car running at a constant speed of V = 10 m / s when the engine is turned off at the end of the second second second and the average speed is 9 m / s in the third second?

Since the end of the second second is the beginning of the third second, the starting velocity in the third second is v = 10m / s, and the average velocity in the third second is 9m / s, so the velocity at the end of the third second is 8m / s, which means that the velocity change in the third second is 2m / s, so the acceleration a = 2m / s