Two trolley 1 and 2 are moving with acceleration `a_(1)` and `a_(2)` respectively, in the same direction. A block of mass m on trolley 1 is in equilibrium from the frame of observer stationary with respect to trolley 2. the magnitude of friction force on block due to trolley is (assume taht no horizontal force other than friction force is acting on block).

Options

A. `m(a_(1)-a_(2))`
B. `ma_(2)`
C. `ma_(1)`
D. Data insufficient

Answer

B

Explanation

Since m is in equilbrium w.r.t. observer, acceleration of m should also be `a_(2)`. So net friction force (as there is no other horizontal force on m) acting on m should be mass `xx` acceleration =`ma_(2)`.