Question
Physics Question on Relative Velocity
Two parallel rail tracks run north-south. On one track train A moves north with a speed of 54kmh−1 and on the other track train B moves south with a speed of 90kmh−1 . what is the velocity of a monkey running on the roof of the train A against its motion with a velocity of 18kmh−1 with respect to the train A as observed by a man standing on the ground ?
A
5ms−1
B
10ms−1
C
15ms−1
D
20ms−1
Answer
10ms−1
Explanation
Solution
Let the velocity of the monkey with respect to ground be vMG . Relative velocity of the monkey with respect to train A , vMG=−18kmh−1=−18×185ms−1=−5ms−1 vMG=vMA+vAG=−5ms−1+15ms−1=10ms−1