Sun July 29, 2012 By:

A man running on a horizontal road at 8 km/h finds the rain falling vertically.He increases his speed to 12 km/h and finds that the drops make angle 30 degrees with the vertical.Find the speed and direction of the rain with respect to the road.

Expert Reply
Sun August 05, 2012
Since when the person runs at 8 km/h the rain seems to be coming verticaly down thus the horizontal component of rain, Vx is 8 km/h
When he incrreases his relative speed by 4 km/h with the horizontal component of rain, it seems to fall at an angle of 30 degrees with the vertical.
It means the vertical component, Vy is: 4/Vy = tan 30
Vy = 6.93 km/h
V = 10.58 km/h
and angle of falling is: tan-1(8/6.93)
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