Question

A bus was moving with a speed of 54km/h .On applying brakes ,it stopped in 8 second . Calculate the acceleration
and the distance travelled before stopping .

Answer 1

Initial speed of the bus (u) = 54 km/h = 15 m/s

Final speed of the bus (v) = 0 m/s

Time taken to stop (t) = 8 seconds

Let the acceleration be a.

$v = u +at$

$a = \frac{v- u}{t}$

$a = \frac{-15}{8}$

a = - 1.875 m/s^2

Now, using third equation of motion

$v^2 = u^2 + 2as$

$s = \frac{v^2 - u^2}{2a}$

$s = \frac{15 \times 15}{ 2 \times 1.875}$

s = 60 m

The distance covered before coming to rest is 60 m.