Question

A train is moving with the speed 5m/s A bullet fired with the velocity 10 m/s crosses the train in 8s what is the length of the train

Answer 1

There can be 2 cases to consider the length of train.

Distance covered by bullet in time = 8 seconds, D = 10×8=80m

Distance covered by train in 8 seconds, d = 5×8=40m

CASE 1

If the train and the bullet are moving in the same direction:

The train covers 40m by the time the bullet crosses it. So the bullet has to cover 40 extra metres to cross the train

Length of train = 80 - 40 = 40metres

CASE 2

If the train and the bullet are moving in opposite direction:

The train covers 40metres moving towards the bullet.. So the bullet has to cover 40 metres lesser to cross the train.

In this case, length of train = 40+80 = 120metres.

Hope this helped!!

Answer 2

Answer:

120 m

Explanation:

distance travelled by train in 8 sec = 8×5m/s=40 m

distance travelled by bullet In 8 sec=8×10m/s= 80 m

as train and bullet are moving in different directions , hence bullet had to move 40 m less than the trains length i.e 80-40 m = 40 m

and hence lenght of train is 80+40=120 m