Given that,
Mass of the stone, m = 400 g = 0.4 kg
Initial speed, u = 20 m/s
It is climbed to a height of 12 m.
To find,
The work done by the resistance force.
Solution,
Let v is the final speed. It can be calculated by using the conservation of energy.
[tex]v=\sqrt{2gh} \\\\v=\sqrt{2\times 9.8\times 12} \\\\v=15.33\ m/s[/tex]
Work done is equal to the change in kinetic energy. It can be given as follows :
[tex]W=\dfrac{1}{2}m(v^2-u^2)\\\\=\dfrac{1}{2}\times 0.4\times (15.33^2-20^2)\\\\=-32.99\ J[/tex]
So, the required work done is 32.99 J.
