Question

Rain is falling vertically with a speed of 35 m per second. will start blowing after some time with a speed of 12 metre per second in east to west direction. in which direction should a boy waiting at the bus stop hold his umbrella?

Answer 1

To the boy , the rain will appear to fall in the direction of the resultant of the rain and wind.

Let ? be the angle which the resultant velocity subtends with the vertical.

Then, tan ? = velocity of wind/ velocity of rain = 12 / 30 = 2 /5

or, ? = tan-1 (2/5)

The boy should hold the umbrella at an angle ? = tan-1 (2/5) south of vertical.