Circular motion with a string with weight

AI Thread Summary
The discussion revolves around a physics problem involving a block of mass m2 attached to a cord of mass m1, moving in a horizontal circle. The key challenge is to find the tension in the cord as a function of the radial position along its length. Participants note the need for an integral equation to account for the mass of the cord, suggesting that the tension varies along its length due to the linear mass density. A misunderstanding arises regarding the influence of the block's mass on the tension calculations, prompting further clarification on integrating the forces involved. The conversation emphasizes the importance of correctly setting up the integral to solve for tension in this circular motion scenario.
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Homework Statement


A block of mass m2 is attached to a cord of mass m1 and length L, which is fixed at one end. (Note, not a massless cord!) The block moves in a horizontal circle on a frictionless table. If the period of the circular motion is P, find the tension in the cord as a functions of radial position along the cord, 0 <_ r <_ L. (<_ meaning greater than or equal to)


Homework Equations


a = v^2/r, F = ma


The Attempt at a Solution


So I could immediately tell that this problem involves setting up an integral equation of some sort. I've learned in class how to solve for integral equations when a block is hanging on a ceiling or things as simple as that, but none of these.
So if L is the distance from the center of the circle to some arbitrary point on the cord, I think the tension at the very end of the cord connected to the mass will just be the centripetal acceleration of the mass multiplied by m1, so there's one of the limits of the integral equation. The other limits should be 0 and L for the radius. The last one will be the unknown for which I have to solve for.
But when I set up my equation and solved for it, I somehow got T(L) = m_1*2*pi*L + T(0), which doesn't make sense.
 

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giggidygigg said:
So if L is the distance from the center of the circle to some arbitrary point on the cord, I think the tension at the very end of the cord connected to the mass will just be the centripetal acceleration of the mass multiplied by m1

Why? Does the mass of the block dissappear? For any point on the string at a distance x, if you assume the linear mass density to be \lambda =\frac{m_1}{L} then the string at that point is \lambda xdx+ m_2. Figure out the variation of x and then integrate.
 
Last edited:
oops i meant m2. but anyway i'll try to carry it out with your advice
 
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