Question

A block of mass $ 2\,kg $ is placed on the surface of a trolley of mass $ 20\,kg $ which is on a smooth surface. The coefficient of friction between the block and the surface of the trolley is $ 0.25 $ . If a horizontal force of $ 2\,N $ acts on the block, the acceleration of the system in $ ms^{-2} $ is $ (g=10\,ms^{-2}) $

• A. 1.8
• B. 1.0
• C. 0.9
• D. 0.09

Answer 1

Answer: (D)

The force of limiting friction between the block and trolley
$ f_1 = \mu R = \mu mg $
$ 0.25 \times 2 \times 10 = 5\, N $

Since, $ F = 2 \, N, F< f_L $
So, both will move together with acceieration
$ a_B = a_T = \frac{2}{20 + 2} $
$ = \frac{1}{11} = 0.09 \,ms^{-2} $