Question

A train is travelling at a speed of 90 km per hour. Brakes are applied so as to produce a uniform acceleration - 0.5 metres per second square. Find how far the train will go before it is brought to rest.

Answer 1

Initial speed of the train, $u=90km/h=90\times \frac{5}{18}=25m/s$

Final speed of the train, $v=0$(finally the train comes to rest)

Acceleration = $a=-0.5m{s}^{-2}$

According to third equation of motion:

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

$0^2={25}^2-2\times 0.5\times s$

Where s is the distance covered by the train

After solving

$s=\frac{(25{)}^2}{2\times 0.5}=625m$

The train will cover a distance of 625 m before it comes to rest.