Relative Velocity
Every motion is relative as it has to be observed with respect to an observer. Relative velocity is a measurement of velocity of an object with respect to other observer. It is defined as the time rate of change of relative position of one object with respect to another.
For example, if rain is falling vertically with a velocity `v_r` and a man is moving horizontally with `v_m`, the man can protect himself from the rain if he holds his umbrella in the direction of relative velocity of rain w.r.t. man.
A girl riding a bicycle with a speed of `5 ms^(-1)` towards east direction sees raindrops falling vertically downwards. On increasing the speed to `15 ms^(-1)`, rain appears to fall making an angle of 45° of the vertical. Find the magnitude of velocity of rain.
Options:
(a) `5ms^(-1)`
(b) `5sqrt5 ms^(-1)`
(c) `25 ms^(-1)`
(d) `10 ms^(-1)`