Chapter 5 - Work and Energy - Learning Path Questions and Exercises - Exercises - Page 175: 15

$13.506kJ$

Force to get the desk moving =$0.75\times mg=0.75\times 100\times 9.8=735N$ Now, $F-coefficient_{kinetic}\times mg=ma$ $735-(0.6\times 100\times 9.8)=100a$ $735-588=100a$ $a=1.47m/s^{2}$ Now, $S=ut+\frac{1}{2}at^{2}=0+0.5\times 1.47\times 5^{2}=18.375m$ Thus, Work =$735\times 18.375=13.506kJ$