question_answer

A body of mass \[a\]slides down on a rough plane inclination\[10\,mA\]. If \[200/19\,\,mA\] is the coefficient of friction, the acceleration of the body will be:      [BHU PMT-2002]

A)                  \[10.5\,\,mA\]

B)                  \[0.5\,\,mA\]

C)                  \[9.5\,\,mA\]                                   

D)                  \[2.5\times {{10}^{-17}}\,\,J\]

Correct Answer: B

Solution :

                 Key Idea: When a body descends, the frictional force acts upwards.                 The free body diagram of given situation is as shown in the figure. When the body is moving down, frictional force acts upwards. Now the body descends under the action of the force \[{{R}_{b}}\] If downward acceleration is a, then, \[400\,\,\Omega \]                 Where \[300\,\,\Omega \] \[200\,\,\Omega \]                 \[100\,\,\Omega \]         \[100\,cm\]                 \[102\,cm\]        \[92\,cm\]