- #1
sbacker
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Homework Statement
A 52.2 kg pole-vaulter falls from rest from a height of 3.6 m onto a foam-rubber pad. The pole-vaulter comes to rest 0.34 s after landing on the pad.
(a) Calculate the athlete's velocity just before reaching the pad.
(b) Calculate the constant force exerted on the pole-vaulter due to the collision.
Homework Equations
Kinematic equations: V = Vo + AT, X = ((V+Vo)/2)*T, V^2 = Vo^2 + 2AX, X = VoT +.5AT^2
F = ma (though I haven't attempted part b yet)
The Attempt at a Solution
It seems like this problem should be easily and quickly solvable using any of the kinematic equations (4 of three values are known, right? Time, distance, acceleration, and original velocity), but this is what I tried and both answers were wrong:
0 = Vo + 9.8 m/s^2 * .34 s (tried 3.33, didn't work)
3.6 = Vo(.34) + .5 * 9.8 *.34^2
3.6 = Vo * .19259 (tried 18.7, didn't work)
I'm a little confused about whether the pole vaulter's mass is irrelevant information, or how to use it—I think I'm a little off with the kinematic equations. Thanks for your help and answers, I know I'm not very good at physics! :)