Question

A car slows down from speed of 72

Answer 1

Explanation:

Given parameters:

Initial velocity = 72km/hr

Final velocity  = 0km/hr

Time taken  = 25s

Unknown:

Acceleration = ?

Solution:

To solve this problem, convert km/hr to m/s;

           1000m = 1km

           3600s = 1hr

  72km/hr;

          1km/hr  = 0.278m/s

         72km/hr = 0.278 x 72  = 20.02m/s

Acceleration is the change in velocity divided by the time taken;

       Acceleration = $\frac{final velocity - initial velocity }{time}$  

       Acceleration  = $\frac{0 - 20.02}{25}$   = -0.8m/s

The car  is actually decelerating at a rate of 0.8m/s