The acceleration of an object is simply the rate of change of velocity. It can also be written as,

a = dv/dt = (v2 - v1)/(t2 - t1)

here, a is the acceleration of the object, v1 and v2 are its velocities at time instants t1 and t2.

In the given case, the object is traveling towards the east direction at 15 m/s initially. That is v1 is 15 m/s. The object's new velocity is 5 m/s, still due east, after 4 seconds. Thus, v2 is 5 m/s and the total time elapsed is 4 sec (= t2 - t1).

Hence, the acceleration of the object is given as:

a = (v2 - v1)/(t2 - t1) = (5 m/s - 15 m/s)/4 sec = (-10 m/s) / 4 sec

= **-** **2.50 m/s^2**

Thus, the car is accelerating at -2.50 m/s^2 or, in other words, it is decelerating (negative acceleration) at 2.50 m/s^2.

Hope this helps.

## We’ll help your grades soar

Start your 48-hour free trial and unlock all the summaries, Q&A, and analyses you need to get better grades now.

- 30,000+ book summaries
- 20% study tools discount
- Ad-free content
- PDF downloads
- 300,000+ answers
- 5-star customer support

Already a member? Log in here.

Are you a teacher? Sign up now