Question

Let's say a thief is running on a train with 12km/h. The police car is moving with 80km/h. If the speed of the train is 60km/h. What is the speed of thief with reference to police car?

Answer 1

If the thief is moving in the direction of the train through the train,his velocity will be sum of the velocity of train and velocity of thief.

So,here,velocity of thief respect to ground=60+12=72km/HR

Police car is moving with a speed of 80km/hr

So,speed of the thief with respect to the police car=

(Speed of thief respect to ground - speed of police with respect to ground.)

=72-80= - 8km/hr

ie,thief is moving with a speed 8km/hr less than police.

Or police is moving forward with a speed 8km/hr more than the thief.

So,police will catch the thief.