## Fundamentals of Physics Extended (10th Edition)

Work done by cord's force $=\frac{-3Mgd}{4}$
Let the cord's force be F. Block's acceleration $=\frac{g}{4}$ Net force = $Ma=M\frac{g}{4}$ Block is going down so, weight($Mg$) is greater. Therefore; $Mg-F = M\frac{g}{4}$ $F = \frac{-3Mg}{4}$ Substituting the formula of $F$ above in $W=Fd$ and simplifying: $W=Fd=\frac{-3Mg}{4}\times d =\frac{-3Mgd}{4}$