Question

As shown in the figure a person is pulling a mass 2 kg from ground on a fixed rough surface up to the top of the surface with the help of a light inextensible string. Find the work done (in Joule) by tension in the string if height of the surface is 1 m from ground, length of base of the surface is 2.5 m and friction coefficient is 0.4. Assume that the block is pulled with negligible velocity.

• A. 20 J
• B. 30 J
• C. 40 J
• D. 50 J

Answer 1

The correct option is C

40 J

$W=mgh+\mu mg\ell =2\times 10\times 1+0.4\times 2\times 10\times \frac{5}{2}=40J$