Concepts Of Physics MCQ Edition [Volume 1]PhysicsFriction
The coefficient of friction between the two blocks displayed in the figure is , whereas the floor is smooth. Assume the complete system is situated inside an elevator that is descending with an acceleration a
Options
- A2 mg and 2 mg m + M
- Bm(g - a) and m(g - a) m + M
- C2 m(g - a) and 2 m(g - a) m + M
- D2 m(g + a) and 2 m(g + a) m + M
Correct answer
C. 2 m(g - a) and 2 m(g - a) m + M
Step-by-step solution
In the frame of the descending elevator, the effective acceleration due to gravity is g_ eff = g - a . The normal reaction between the block of mass m and the block of mass M is N = m(g - a) . The maximum static friction force between the two blocks is f_ max = N = m(g - a) . Let T be the tension in the string. For the system to remain in equilibrium, the net force on each block must be zero. With the impending motion of m to the left, the friction force f on m acts to the right, and the friction force on M acts to