Centripetal Acceleration with Tarzan

1. Feb 29, 2012

PeachBanana

1. The problem statement, all variables and given/known data
Tarzan plans to cross a gorge by swinging in an arc from a hanging vine, as shown in the figure.
If his arms are capable of exerting a force of 1200 N on the vine, what is the maximum speed he can tolerate at the lowest point of his swing? His mass is 100 kg, and the vine is 4.5 m long.

2. Relevant equations
Tension force - mg = ma
(a * r)^1/2 = v

3. The attempt at a solution

1400 N = (100 kg)(a)+(100 kg)(9.8m/s^2)
420 N = 100kg * a
a = 4.20 m/s^2

(4.20 m/s^2)(2.25m)^1/2 = v

Why is it incorrect to use 2.25 m as the radius? They gave the entire length of the vine.

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• TARZAN.jpg
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2. Feb 29, 2012

BruceW

If you look at the picture, what point is tarzan 'orbiting around' ?

3. Feb 29, 2012

genericusrnme

I lol'd

The picture reminds me of a picture on one of the exams I did a while back in highschool, there's some bizarre half black half white basketball playing hybrid

Also, what BruceW said

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4. Feb 29, 2012

PeachBanana

Oh I see. That's more clear. He's orbiting around the very top of the tree, not the middle of the vine.