Question

A 70 kg man leaps vertically into the air from a crouching position. To take the leap, the man pushes the ground with a constant force f to raise himself. The centre of gravity rises by 0.5 m before he leaps. After the leap, the centre of gravity rises by another 1 m. The maximum power delivered by the muscles is:

Answer 1

According to the conservation of energy,

⇒12mv2=mgh

As h=1m; ⇒v=2g−−√

Maximum power by muscles at take:

⇒P=2Fv=2×mg×2g−−√=2×70×10×20−−√

=6260.8=6.26×103W/s

Answer 2

This is how I do it.

Hope it helps