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Rain is falling vertically with a speed of 30 m/s. wind starts blowing after some time with a speed of 15 m/s in east to west direction. In which direaction should a boy waiting at a bus hold his umbrella ? |
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Answer» Solution :The direction in which boy should hold his umbrealla is opposite to resultant velocityof rain and wind. Let vertically up bey-axis and WEST to east be x -axis. Now, ` vecv_(R) = - 30hatj , vecv_(w)jj = - 15 hatj` Theresultant velocity of rain and wind is `vecv_(R) + vecv_(w) = -30 hatj - 15 hatj ` From , the figure , ` tan tehta = 15/20 = 1/2` ` Rightarrow THETA = tan^(-1) (1/2)` So, the boy should hold his umbrealla inclined at an angle ` tan^(-1)(1/2)`with vertically ,TOWARDS east. 
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