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## Homework Statement

A bungee jumper of mass 64.5 kg (including safety gear) is

standing on a platform 48.0 m above a river. The length of

the unstretched bungee cord is 10.1 m. The force constant

of the cord is 65.5 N/m. The jumper falls from rest and just

touches the water at a speed of zero. The cord acts like an

ideal spring. Use conservation of energy to determine the

jumper’s speed at a height of 12.5 m above the water on

the first fall.

## The Attempt at a Solution

so I decided that Eg(at the top of the platform)=Ek+Ee+Eg'(12.5 above water floor)

so for h initial i used 48m...h'= 12.5m and x(stretch of the cord)= 25.5m

therefore

mg(48)=.5k(25.5^2)+.5mv^2+mg(12.5)

i solved for V and got 5.96m/s, the answer is 6.37m/s...please help!!