Two parallel rail tracks run north-south. Train A moves north with a speed of 54kmh^(-1), and train B moves south with a speed of 90kmh^(-1). What is the (a) velocity of B with respect to A? (b) velocity of ground with respect to B?And (c ) velocity of a monkey running on the roof of the train A against its motion (with a velocityof 18 kmh^(-1) with respect to the train A) as observed by a man standing on the ground?

Two parallel rail tracks run north-south. Train A moves north with a s

1.	Two parallel rail tracks run north-south. Train A moves north with a speed of 54kmh^(-1), and train B moves south with a speed of 90kmh^(-1). What is the (a) velocity of B with respect to A? (b) velocity of ground with respect to B?And (c ) velocity of a monkey running on the roof of the train A against its motion (with a velocityof 18 kmh^(-1) with respect to the train A) as observed by a man standing on the ground?
Answer» Solution :`v_(A)=+54kmh^(-1)=15ms^(-1)` `v_(B)=-90kmh^(-1)=-25ms^(-1)` Relative velocity of B with respect to A is `V_(BA)=V_(B)-V_(A)=-40MS^(-1)` i.e. the train B appears to A to move with a SPEED of 40 m s-1 from NORTH to south. Relative velocity of ground with respect to B is `V_(GB)=0-v_(B)=25ms^(-1)` In (c ), let the velocity of the monkey with respect to ground be `v_(M)`. Relative velocity of the monkey with respect to A. `v_(MA)=v_(M)-v_(A)=-18kmh^(-1)=-5MS^(-1)` Therefore, `v_(M)=v_(MA)+v_(A)=(-5+15)ms^(-1)=10ms^(-1)`.