Tension in a circular wire with force radiating outwards

AI Thread Summary
A uniform circular wire with a radius r experiences a total outward force of 10N from its center. The tension in the wire is calculated by integrating the force components acting on the semicircles. Initially, the tension was thought to be 10/π, but it was clarified that this force is distributed evenly, leading to a final tension of 5/π. The importance of drawing a free body diagram was emphasized to accurately assess all forces acting on the wire. The discussion confirms the correct approach to solving the problem while highlighting the need for careful consideration of force distribution.
hyperddude
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Homework Statement



Let's say there's a uniform circular wire with radius r. There is a uniform force pushing outward from the center in all directions of the wire. This total force is 10N. What is the tension in the wire?

Homework Equations



N/A

The Attempt at a Solution



Let's say the circle is on an xy coordinate axis with its center at the origin. I think the tension is equal to the total force in the y-direction on the top semicircle. The y-component of the force on the bottom semicircle will be equal in magnitude and in the opposite direction.

To find the the force, we integrate. dF = \frac{10}{2\pi r} dL. For the component in the y-direction, dF = \frac{10}{2\pi r} \sin{θ} dL by some simple geometry. dL = rθ, so we now have dF = \frac{10}{2\pi} \sin{θ} dθ. Integrating from θ=0 to θ=\pi, we get that F=\frac{10}{\pi}, which is the tension.

I'm moderately sure my math is correct, but my real question is whether I found the tension! I'm not very sure if this correctly defines the tension in the circle.
 
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hyperddude said:
dL = r\sin{θ}
You mean dL = r dθ, right?
Your method is right, but you have overlooked one detail. Draw the free body diagram for one half of the loop. What are all the forces?
 
haruspex said:
Your method is right, but you have overlooked one detail. Draw the free body diagram for one half of the loop. What are all the forces?

Oh, the force I found, \frac{10}{\pi} wouldn't be the tension because the force gets divided evenly into 2. Then the tension would be \frac{5}{\pi}?
 
Yup.
 
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