Does Tarzan's Vine Hold During His Daring Swing?

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Homework Help Overview

The problem involves Tarzan swinging from a cliff using a vine, with a focus on calculating the maximum tension in the vine and determining if it breaks during the swing. The subject area includes mechanics, specifically concepts related to forces, energy conservation, and tension in a pendulum-like motion.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to analyze the forces acting on Tarzan at the lowest point of the swing and equate gravitational potential energy to kinetic energy to find velocity. They express uncertainty about how to find the angle at which the vine might break.

Discussion Status

Some participants question the assumptions made about potential energy at the starting point of the swing, suggesting that Tarzan must have had potential energy due to his initial height. Clarifications and corrections are being discussed, but no consensus has been reached regarding the initial conditions or the method to find the breaking angle.

Contextual Notes

The problem involves specific numerical values for weight and length of the vine, and participants are navigating the implications of these values on the calculations. There is a mention of a figure that is not available to all participants, which may affect their understanding of the problem setup.

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Homework Statement


Tarzan, who weighs 678 N, swings from a cliff at the end of a convenient vine that is 16.0 m long (see the figure). From the top of the cliff to the bottom of the swing, he descends by 3.2 m. A) If the vine doesn't break, what is the maximum of the tension in the vine? B) The vine will break if the force on it exceeds 928.6 N. Does the vine break? If yes, at what angle does it break


Homework Equations


F=ma, Emec=Δk+ΔU, F=mv2/r


The Attempt at a Solution


A) here is my thought process to this problem, if i am wrong in my approach please correct me...tarzan starts at let's say point 1 with no potential energy, but has kinetic energy as he begins his swing. At the bottom of his swing (lowest point) will be where the max tension will occur. So, F=ma becomes F=mv2/r and you also have mgh=1/2mv2 because he drops 3.2m so by figuring out the GPE and equating that to the final KE (bottoms of swing) you will derive the velocity at the bottom of the swing. i end up with F=mg(1+2h/r) and get 949.2 N which is correct.
B) i have no idea how to find the angle where it breaks at or even how to derive the formula...this is where i am hoping someone can guide me in the right direction (how to analyze the problem).

Thank you for your time!
 
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matt57017 said:
tarzan starts at let's say point 1 with no potential energy

I believe that is an incorrect statement. I don't have the picture to go off of, but in the problem, it says he descends 3.2m, which means he would have had to have started at least 3.2m off the ground, if not more. In this case, he would have potential energy.
 
Yosty,

that is true my fault. i have attached a picture for further clarification.
 

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Yosty22 said:
I believe that is an incorrect statement. I don't have the picture to go off of, but in the problem, it says he descends 3.2m, which means he would have had to have started at least 3.2m off the ground, if not more. In this case, he would have potential energy.

You can define potential energy to be zero wherever you'd like, provided you're alright with using negatives.
 

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