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ritwik06

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## Homework Statement

A U shaped smooth wire has a semi circular bending between A and B (A and B are points on the U wire). A bead of mass 'm' moving with uniform speed v through the wire enters the semi circular bend at A and leaves at B. Find the average force exerted by the bead on the part AB of the wire. d is the perpendicular distance between the two arms of the U shape.

## The Attempt at a Solution

Method 1:

As the part betwen A and B is circular

Force=mv^2/ (d/2)

Method 2:

The change in momentum is 2mv

time taken to go around AB=pi*(d/2)*(1/v)

Force =change in momentum/timeI get two different answers from these 2 methods. At least one of them is surely wrong. but which one? Both seem right to me.

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