Tarzan the ape man

Classical Mechanics Level 4

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Tarzan , who weighs 800N , swings from the cliff at the end of a vine 20 m long (see figure).

From the top of the cliff to the bottom of the swing, he descends by 5 m.The vine will break if the force on it exceeds 1250 N.
What is the greatest force (in N) on it during the journey.

Details :

  • If you thinks vine breaks during the swing, put your answer as 0.
  • Take g = 10 m / s 2 g = 10 m/s^2


The answer is 1200.

Akhil Bansal by Akhil Bansal , 22, India

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1 solution

At the lowest point, the velocity is maximum , thus force is maximum.

For that point, Force, f = m g + m v 2 l f=mg+m\frac{v^2}{l}

Here, l = length of the vine = 20 m l=\text{length of the vine}=20m

m g = w e i g h t = 800 N mg=weight =800\text{N}

And, m = 800 10 k g = 80 k g m=\frac{800}{10}kg=80kg

Now, for velocity, v 2 = 2 g h v^2=2gh Here, h = maximum descend = 5 m h=\text{maximum descend} =5m

Finally, f = ( 800 + 80 × 10 × 5 20 ) N f=(800+\frac{80\times10\times5}{20})\text{N} = 1200 N =1200\text{N}

Done!

1 Helpful 0 Interesting 0 Brilliant 0 Confused

Nice solution.

Akhil Bansal - 5 years, 8 months ago

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The upvote would be enough for my reward! Thank you!

Muhammad Arifur Rahman - 5 years, 8 months ago

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Oops! I forgot that..

Akhil Bansal - 5 years, 8 months ago

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@Akhil Bansal – Thank you! Have you joined Brilliant Lounge ?

Muhammad Arifur Rahman - 5 years, 8 months ago

I just guessed but by equaling by 10

Krishna Mandal - 5 years, 8 months ago

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That's brilliant.

Muhammad Arifur Rahman - 5 years, 8 months ago

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