Question

A train starting from rest attains a velocity of ` 72 km//h` in 5 minutes . Assuming that the acceleration is uniform , find (i) the acceleration and (ii) the distance travelled by the train for attaining this velocity .

Answer 1

We have been given
`u=0, v=72 km h^(-1)=20 m s^(-1)` and t=5 minutes =300s
(i) From Eq. (8.5) we know that
`a=((v-u))/(t)`
`=(20 ms^(-1)-0 ms^(-1))/(300 s)`
`=(1)/(15) m s^(-2)`
(ii) From Eq. (8.7) we have `2a s=v^(2)-u^(2)=v^(2)-0`
Thus ,
`s=(v^(2))/(2a)`
`=((20 ms^(-1))^(2))/(2xx(1//15)ms^(-2))`
3000 m
3 km
The acceleration of the train is `(1)/(15) ms^(-2)` and the distance travelled is 3 km.