Question

The velocity of a car decreases from 20 m/s to 10 m/s in a certain time interval. Find its retardation if the distance covered during this time is 300 m.

Answer 1

Step 1, Given data

Initial velocity = 20 m/s

Final velocity = 10 m/s

Distance covered = 300 m

Step 2, Finding the retardation

Let the retardation be 'a'.

From the third equation of motion,
$v^2=u^2-2as$

Putting all the values
$\Rightarrow {10}^2={20}^2-2\times a\times 300$
$\Rightarrow 100=400-600a$
$\Rightarrow a=0.5m/s^2$

Hence the retardation is 0.5 m/$s^2$