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Scorching goIITian

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10 Sep 2009 19:16:05 IST
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A question on finding trajectory of a particle
Kinematics , NewtonsLawsCirMotion , Work Power Energy collisions , Rotation , Gravitation , Simple Harmonic Motion , Fluid Mechanics , Materials Wave Sound , Super Position , units dimensions , com momentum , shm , wave sound

 Respected experts, I am in need of your help. This is a question which I can not determine how to approach, how to proceed, what concepts are involved,...nothing! I would be very grateful if you could guide me to the correct method to solve this problem. Here goes the question:

"A particle is placed on a rough plane inclined at an angle theta, where tan θ = μ = coefficient of friction(both static an dynamic). A string attached to the particle passes through a small hole in the plane. The string is pulled so slowly that you may consider the particle to be in static equilibrium at all times. Find the path of the particle on the inclined plane."


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adi's Avatar

Blazing goIITian

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10 Sep 2009 19:18:32 IST
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can u draw the diagram

Scorching goIITian

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10 Sep 2009 19:23:23 IST
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 Sure, here is the diagram given in the book:

adi's Avatar

Blazing goIITian

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10 Sep 2009 19:25:43 IST
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wait for five minutes 


Scorching goIITian

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11 Sep 2009 15:53:25 IST
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Experts, please help!
adi's Avatar

Blazing goIITian

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11 Sep 2009 16:24:16 IST
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experts !!!help ................there are many answered questions and no ne is taking initiative to solve

Sunny's Avatar

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12 Sep 2009 22:17:32 IST
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experts help...plzzzz

NugoRama's Avatar

Blazing goIITian

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21 Sep 2009 17:08:34 IST
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Niche-=of=-rocketS GODSPEED's Avatar

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21 Sep 2009 17:46:35 IST
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Dear Anshul'Please check this out.coeff. of static friction= coeff. of dynamic frictionTherefore, when force is applied in the dir. of hole it is this direction in which the object will move.Given, at all times the particle is in static equilibrium all other forces on it cancel each other.
NugoRama's Avatar

Blazing goIITian

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21 Sep 2009 23:56:01 IST
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rite... thats the case when the coeff of friction is good enuff to balance gravity. The other( and i mean..the general ) case is rather complicated.. agreed the string is being pulled down at negligible rate..but that does not imply that the particle wont slide... hence, in this case..the trajectory will be a combination of 2 linear motions ..one accelerating and other non-accelerating. ONE MORE POINT : had the stable equilibrium thing wudnt be there...khair chaddo ..any takers ?

Niche-=of=-rocketS GODSPEED's Avatar

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22 Sep 2009 22:34:51 IST
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THX NUGO
NugoRama's Avatar

Blazing goIITian

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22 Sep 2009 22:35:20 IST
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abhi solve nahi hua hai dost ...
Lakshya Bhardwaj's Avatar

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27 Sep 2009 11:58:33 IST
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I think the particle will move on the incline in a parabola with its opening upward on the incline in the most practical case. I have reasoned as follows:Normal and a component of gravity balance each other out. That's nothing special in that. Now, the component of tension along the incline parallel to the base will pull the particle horizontally. Now, considering it practically the tension's component will be greater that friction's component. Again, the other components of tension and gravity which act along the incline perpendicular to the base will add up and the other component of friction counteracts them. Again, from here on we would again get 3 more cases. But, trying to solve the problem practically, we can consider friction not able to balance gravity and tension.In a short conclusion, although there are more than 9 cases possible for the whole problem, a practical answer would be that it goes around in a parabola with its mouth up along the incline.

Scorching goIITian

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28 Sep 2009 09:10:01 IST
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Looks like now people are beginning to take interest.

But the answer's given as a circle, in this form : x^2 + y^2 = cy.

Anyway, Lakshya, how did you get it as a parabola? The reasoning's fine, I'd also got to that, but how did you conclude that it is a parabolic path? Waiting for you to shed some more light on it, may be it will be enlightening for us all.

Soumen Goswami's Avatar

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2 Oct 2009 21:20:35 IST
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Scorching goIITian

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12 Oct 2009 16:35:46 IST
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Sorry to say this, sir, but I don't think this solution is completely correct.

This is because you have taken T as a constant, which is not true. In fact, T changes such that the system is in static equilibrium.

You can verify this by just looking at your answer, the reported equation is x^2 + (1-k)y^2 = 0, and this equation does not give any curve if 1-k is positive, and gives 2 straight lines if 1-k is negative. So, you see, this is not the correct answer.

I think the discussions should START AGAIN!


Scorching goIITian

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12 Oct 2009 16:38:01 IST
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Has anyone else got the answer?




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