A rain is falling with a speed of 35m/s.Wind starts blowing after sometime with a speed of 12 m/s in east to west direction. In which direction should the boy hold his umbrella to protect himself?

Asked by  | 13th Aug, 2011, 12:00: AM

Expert Answer:

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.

Answered by  | 14th Aug, 2011, 03:53: AM

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