Question

A mass of $2kg$ is placed on a trolley of $20kg$ sliding on a smooth surface. The coefficient of friction between the mass and surface of trolley is $0.25$. A horizontal force of $2N$ is applied to the mass. The acceleration of the system and the frictional force between the mass and the surface of trolley are:-

• A. $1.8{ms}^{-2},0.09N$
• B. $0.9{ms}^{-2},18N$
• C. $0.09{ms}^{-2},1.8N$
• D. $1{ms}^{-2},2N$

Answer 1

The correct option is C $0.09{ms}^{-2},1.8N$

Here the limiting friction force $=\mu mg=0.25\times 2\times 10=5N$
Thus the applied force is less than the friction force. So there will not have relative motion in between trolley and mass.
therefore, $2=(20+2)a\Rightarrow a=0.09m/s^2$
The friction force between mass and surface of trolley $=20a=20\times 0.09=1.8N$