The situation in the question has been experimented my most of us in our childhood, but no one probably thought of this!
There is a thread of mass M and length L is stretched on a smooth horizontal surface with constant forces acting on either sides of the rope. A sudden movement causes the rope to form a circular loop traveling traveling from one end of the rope, with constant velocity v .
If:
Evaluate ∣ v ∣ + ∣ ℓ ∣ + ∣ K E ∣ . Give your answer to 3 decimal places.
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This is the best kind of problem, a simple situation everyone has seen but few have calculated. How would this change in the presence of a gravitational field?
But I hope you give the final value too
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Why? You can find it by substituting right?
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Was a very easy question, got it in 1st attempt. but as I say , every thought is unique and classy. :) . Thumbs up. keep posting.
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@Pranjal Prashant – Thanks! Sure!
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@Kishore S. Shenoy – Can you post a level 5 questions for ninth graders (well, I have joined fiitjee classes so can you just make it difficult but please for a ninth grader)
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@Department 8 – well I have seen few questions that are really easy. For instance question titled abstract pac man . My questions, first mechanics problem, awa others are very easy to solve too. Though they have level 4 rating as many people solved it.
@Kishore S. Shenoy – 400 points now
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@Pranjal Prashant – ?? Why did you mention that now?? I think that's the maximum a question can get in Brilliant
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@Kishore S. Shenoy – yes, it is max. well this one was deserving it. I can easily solve the difficult problems (almost :p) . But posting such good ones is a nightmare. Tried to post my own difficult maths problem but it had so many typing and formatting errors that I had to delete it.
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@Pranjal Prashant – Hehe, happened to me once or twice. One is just happening... Check this one
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@Kishore S. Shenoy – Sorry for the late reply. There were exams.... . And I solved that question too. Meanwhile I was going through your physics set and it's one of the best after rounak's level 5 and aman's hot integral. P.s. I have completed hot integrals. First one to complete the set . Feeling blessed. :)
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@Kishore S. Shenoy – I will solve them when I login on pc. There is some problem in posting answer on my mobile device.
@Kishore S. Shenoy – And just looking at the tabs, I want to know how was your exam ? I am getting 69. Made lots of silly mistakes there.
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@Pranjal Prashant – You got good. I wrote Online Exam, so... you know right?
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@Kishore S. Shenoy – Know what? ??
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@Pranjal Prashant – I don't know which were the answers I marked. So, I can't get marks... ⌢ ¨
@Kishore S. Shenoy – Solved every question except the day dreamer. It is deleted ¿¿ :)
@Pranjal Prashant – Try my New Earth question!
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@Kishore S. Shenoy – Done ! And one more thing, you are waiting for which moment? Level 5 in number theory?
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@Pranjal Prashant – And Level 5 in Electricity and Magnetism. Studying for it! I don't know anything on it! BTW, are you a moderator here?
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@Kishore S. Shenoy – NONONONO, I am not a moderator. Just a good solver. Posting up questions or editing them is miles out of my way. And perhaps you are in 11. Otherwise you easily would have level 5 in E&M.
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@Pranjal Prashant – Yup. I'm in 11th and in 12th you learn E&M! Nice to meet you! You are in 12th?
@Pranjal Prashant – Why don't you try solving A long Slipway?
@Calvin Lin , sir, if you are the Challenge Master, when there is gravitation, the net force will not be zero and thus we can't use the first equation.
Source of the question ?? And please give computable figures, calculation was humongous.
how did u write the first equation
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Really sorry for replying late. I was busy with my courses. Check out the solution for this problem for the derivation of that equation.
Does this really happens?? I have never seen it in reality!
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As no one has given a solution till now, I am giving now.
If we consider the motion of the loop in the centre of the loop frame, the loop performs uniform rotation. With this in mind, we can use
T = ρ v 2
where T is the tension, ρ is the linear mass density, and v is the speed of all elements of the loop.
Now, we know F = T
⇒ v = M F L
So that ℓ = I ω = 2 π R ρ R 2 R v = 2 π R 2 L M F ⇒ ℓ = 2 π R 2 L M F
And, K E t o t = I ω 2 = 2 π R ρ v 2 = 2 π ρ R ρ F ⇒ K E = 2 π R F
∴ v + ℓ + K E = M F L + 2 π R 2 L M F + 2 π R F