InterviewSolution
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InterviewSolution
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Ten one rupee coins are put on stop of one another on a table Each coin has a mass m kg Give the magnitude and direction of (a) the force on the 7 th coin (counted from the botton ) due to all coins above it (b) the force on the 7 th coin by the eighth coin and (c) the reaction of the sixth coin on the seventh coin. |
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Answer» (a) The force on 7 th coin is due to weight of the three coins lying above it Therefore ` F = (3 m ) kg f = (3 mg ) N ` where g is acceleration due to gravity . This force acts vertically downwards . (b) The eighth coin is alredy under the weight of two coins above it and it has its own weight too . Hence force on 7 th coin due to 8 th coin is sum of the two forces i . e ` F = 2 m + m = (3 m ) kg f = (3 mg ) N ` The force acts vertically downwards . (c) The sixth coin is under the weight of four coins above it Reaction ` R = - F = - 4 m (kg f ) = - (4 mg ) N ` Minus sigh indicates that the reaction acts vertically upwards opposite to the weight . |
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