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akgtdoskce
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Homework Statement
A 102kg man bungee jumps with a 20ft (~6m) cord (k=167 N). Air resistance is 12N.
1. What should be the minimum height of the platform the man jumps off?
2. What is the maximum velocity he will reach?
3. How high will he bounce up the first time?
Homework Equations
Uelastic_initial+ KEinitial + Ugravity = Uelastic_final + KEfinal + Ugravity
Elastic Potential Energy= 1/2kx^2
Kinetic Energy= 1/2mv^2
Gravitational Potential Energy= mgh
mgh = (1/2)k(h-L)^2, where L is unstretched distance
The Attempt at a Solution
I've seen a lot of threads on similar bungee jumping problems, but I'm still not clear how the 12N air resistance would factor in. I know W=Fd so the air resistance would be multiplied by displacement, but beyond that I'm not sure where to add/subtract when applying conservation of energy.
Am I right in thinking that the equation mgh = (1/2)k(h-6)^2 could be used if air resistance is negligible? If so, how could I adjust for the 12N air resistance?
(Also, any additional help on the three questions would be much appreciated... I feel like the correct thinking to get the answers is way beyond me)