Answer
The elastic potential energy of the net is $~~8580~J$
Work Step by Step
Note that from the point where the man jumped to the point where the net is stretched, the total distance is $12.5~m$
When the net is stretched by $1.50~m$, the elastic potential energy stored in the net is equal to the initial gravitational potential energy.
We can find the elastic potential energy of the net:
$U_e = U_g$
$U_e = mgh$
$U_e = (70.0~kg)(9.8~m/s^2)(12.5~m)$
$U_e = 8580~J$
The elastic potential energy of the net is $~~8580~J$
