Direction of umbrella

Asked by  | 21st Jul, 2009, 06:20: PM

Expert Answer:

Let us consider the following example to understand how to find the direction in which the umbrella should be held; when the velocity of rain as well as the person is given.

Q. Rain is falling vertically with speed of 30 m/s. A woman rides a bicycle with a spedd of 10 m/s in N to S direction. In which direction should she hold the umbrella?

A. Let vr (vector) be the velocity of rain and v (vector) be the velocity of woman. To the woman the rain will appear to come from the direction of vr - v (vector) . Therefore, the woman should hold the umbrella in the direction of 

 vr - v (vector) which is given by θ .

tan θ = v / vr   = 10 / 30 = 1/3

i.e. she should hold the umbrella at an angle θ = tan -1 ( 1/3) south of vertical.

 

Answered by  | 25th Jul, 2009, 06:52: PM

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