Question

A string is used to pull a block of mass m vertically up by a distance h at a constant acceleration $\frac{g}{3}.$ The work done by the tension in the string is

• A. $\frac{2}{3}$ mgh
• B. $\frac{-mgh}{3}$
• C. mgh
• D. $\frac{4}{3}$mgh

Answer 1

The correct option is D $\frac{4}{3}$mgh

$\begin{array}{c}Tension=m\left(g+a\right)\\ =m\left(g+\frac{g}{3}\right)\\ =\frac{4mg}{3}\\ Workdone=Tension\times Displacement\\ =\frac{4mg}{3}\times h\\ =\frac{4}{3}mgh\end{array}$

Hence,

option $\left(D\right)$ is correct answer.