Question

a man whose mass is 100kg climbs a tree in 20 seconds and expends a power at 150 watts. how tall is the tree

Answer 1

The power

$$P=\frac{\rm{work\; done}}{\rm{time}}=\frac{mgh}{t}$$

So, the height of a tree

$$h=\frac{Pt}{mg}$$ $$=\frac{150\:\rm{W}\times 20\:\rm{s}}{100\:\rm{kg}\times 10\:\rm{N/kg}}=3\:\rm{m}$$