A car traveling north with a velocity of 30 m/sec slows down to a velocity of 10 m/sec within 10 sec. What is the car's acceleration?

-2m/s/s

Explanation:

Acceleration = change in speed / change in time

Change in speed = final speed - initial speed

In this case the change in speed was 10m/s - 30m/s = -20m/s

And change in time was 10 sec (within 10 sec)

Therefore acceleration = -20/10 = -2m/s/s

The acceleration is negative because the car slowed down (decelerated essentially) and the unit for acceleration is meters per second per second because it is the change in speed per second.

Hope this helped!

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