Need help with HW (Potential and Conservation of Energy Problem)?

Question

Catching a wave, a 64 kg surfer starts with a speed of 1.3 m/s, drops through a height of 1.75 m, and ends with a speed of 8.2 m/s. How much nonconservative work was done on the surfer?

Answer 1

Ke1 + Pe + W= Ke

0.5mV1^2 +mgh +W=0.5mV2^2
W=-0.5mV1^2 -mgh+0.5mV2^2
W=-0.5m( V1^2 -2gh + V2^2 )
W=-0.5 x 64((1.3)^2 -2 x 9.81 x1.75 + (8.2)^2)=
W=1000 J