A train is moving in south with a speed of 90 ${\mathrm{kmh}}^{-1}$. The velocity of ground with respect to the train is:

1.  0 ${\mathrm{ms}}^{-1}$

2.  -25 ${\mathrm{ms}}^{-1}$

3.  25 ${\mathrm{ms}}^{-1}$

4.  -40 ${\mathrm{ms}}^{-1}$

Two parallel rail tracks run north-south. Train A moves north with a speed of 54 ${\mathrm{kmh}}^{-1}$, and train B moves south with a speed of 90 ${\mathrm{kmh}}^{-1}$. The magnitude of the velocity of B with respect to A is:

1.  40 ${\mathrm{ms}}^{-1}$

2.  0 ${\mathrm{ms}}^{-1}$

3.  25 ${\mathrm{ms}}^{-1}$

4.  15 ${\mathrm{ms}}^{-1}$

A train is moving in the north direction with a speed of \(54\) ${\mathrm{kmh}}^{-1}$. The velocity of a monkey running on the roof of the train against its motion (with a velocity of \(18\) ${\mathrm{kmh}}^{-1}$ with respect to the train) as observed by a man standing on the ground is:
1. \(40\) ms^-1
2. \(0\)
3. \(-5\) ms^-1
4. \(10\) ms^-1