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a block of ma...

Question

a block of mass 8kg is placed on the rough horizontal surface having coefficient of friction 0.1 . a horizontal force of 20N is applied on block . calculate work done by external force , friction force.

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Solution

$T h e e q n o f m o t i o n o n t h e r o u g h r o a d i s g i v e n b y, m a = F - μ m g o r 8 \times a = 20 - 0.1 \times 8 \times 10 = 20 - 8 = 12 t h e r e f o r e a = 12 / 8 = 3 / 2 m / s^{2} . t h u s t h e w o r k d o n e b y e x t e r n a l f o r c e W_{e x} = m a \times S . W h e r e d i s \tan c e m o v e d i s S . W_{e x} = 8 \times \frac{3}{2} S = 12 S . a n d w o r k d o n e b y f r i c t i o n a l f o r c e W_{f r i c t i o n} = μ m g S = 8 S .$

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