InterviewSolution
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InterviewSolution
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A plank of mass 10 kg and a block of mass 2 kg are placed on a horizontal plane as shown in the figure. There is no friction between plane and plank. The coefficient of friction between block and plank is 0.5 .A force of 60 N is applied on plank horizontally. In first 2 s the work done by friction on the block is A. `-100 J`B. 100 JC. zeroD. 200 J |
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Answer» Correct Answer - B (b) Maximum acceleration of 2 kg block due to friction can be `mu g or 5 ms^(-2)`. Combined acceleration, if both move together with same acceleration would be, `a=(60)/(12)=5ms^(-2)` Since, both accelerations are equal, upper block will move with acceleration `5ms^(-2)` due to friction. In first two seconds, `s=(1)/(2)at^(2)=(1)/(2)xx5xx4=10m` and force of friction, f=ma=10 N `:. " " W_(f)=fs cos0^(@)=100J` |
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