Question

a car is moving at a speed of 18km/h. it starts retarding uniformly at 1m/s^2 and comes to the rest find the distance travelled.

Answer 1

Solution:-
It's given that,
Initial velocity=18km/h

To convert it into m/s we will multiple it with 5/18.
$= > 18 \times \frac{5}{18} \\ = > 5m \: per \: second$
So,
Initial velocity=5m/s
Final velocity=0
Acceleration= -1m/s^2
Time=?

By using equation,(I.e.)
v=u+at
$0 = 5 + ( - 1) \times t \\ 0 = 5 - t \\ t = 5$
So,
time=5 second
Now,
we will find the distance by using equation:-
$s = ut + \frac{1}{2 } {at}^{2} \\ s = 5 \times 5 + \frac{1}{2} \times ( - 1) \times 25 \\ s = 25 - \frac{25}{2}$

$s = \frac{50 - 25}{2} \\ s = \frac{25}{2} \\ s = 12.5m$
Hence,he travelled 12.5meters.