(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

"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."

m=64.5 kg

fconstant= 65.5 N/m

dT=48.0m

v3=0 m/s

unstreched bungee cord = 10.1 m

y2 = 12.5m

RTF = v2

2. Relevant equations

W=0

Et1=Et2

3. The attempt at a solution

I drew a diagram first of total distance 48.0 m. There is 10.1 down from the top and 12.5 m up from the bottom.

I make x1 the distance that remains

So: x1 = 48.0-10.1-12.5 = 37.9m

x2= x1+12.5 = 25.4

0 = ΔEg+ΔEk+ΔEe

(Rearrange)

v2 = sqrt(2(mgΔy+1/2m(vsub3)^2+1/2k(xsub2)^2 -1/2k(xsub1)^2)/m)

(at bottom, the velocity(vsub3) is 0, I plug in #s)

= 23.6 m/s (books says 6.37 m/s)

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# Homework Help: Gr12 Energy Prob (Bungee)

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