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x2017
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Homework Statement
The above image shows Yelena Isinbayeva (64.1 kg) at a point in her vault where the pole is maximally deflected (Δx = 1.63 m). The pole has a bending stiffness of 1091 N/m and behaves according to Hooke's Law. At this point in the vault, her vertical velocity is 3.25 m/s and she is 2.48 m above the ground.
How much work was done be gravity during the time the vaulter went from 2.48 m above the ground to her peak height?
Homework Equations
P=W/t
work done = change in energy
Hooke's Law: Fs=kΔx
Ws=(1/2)kΔx2
KE=(1/2)mv2
PEg=mgh
SE=(1/2)kΔx2
Total energy = KE+PE+SE
W=FΔd
I have already calculated the following from previous questions
Work done on the pole = 1449.34J
SE stored in the pole = 1449.34J
Force applied to the pole = 1778.33N
KE in vertical direction = 338.53J
PEg = 1559.48J
Peak height of her centre of mass = 5.32m
The Attempt at a Solution
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I tried:
W=FΔd
W=(1778.33)(5.32-2.48)
W=5050.46
PEg=mgh
PEg=(64.1)(9.81)(5.32-2.48)
PEg=1785.85
Ws=(1/2)(1090)(5.32)(2.48)2
Ws=4395.75
These answers are all incorrect. I'm not sure how to approach this problem in another way.
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