Pendulum measuring the restorative force HELP

AI Thread Summary
The discussion focuses on deriving an expression for mass in a pendulum system using a force meter. The pendulum's length and angle are considered, with the radial and tangential forces analyzed. It is noted that the radial force due to gravity is balanced by the tension in the string, while the tangential force is unbalanced, driving the pendulum back to equilibrium. The force meter measures this tangential force, which is crucial for finding mass. The participant ultimately understands the relationship between these forces and how to approach the problem.
milk242
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Pendulum measuring the restorative force HELP!

Homework Statement


A pendulum with length L is suspended at an angle theta. At the bottom of the pendulum, a string is attached to force meter. The string attached to the force meter is perpendicular to the pendulum string. In terms of F and theta, find an expression for mass.

Homework Equations


Fg= -mg
(Fg)r = -mgcos(theta)
(Fg)t = -mgsin(theta)

The Attempt at a Solution


What I get is all the tangential and radial components cancel out equally zero, which I would expect because mass doesn't matter in a pendulum. So I don't understand how I'm suppose to obtain an expression for mass.
 

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Hi milk242, welcome to PF.
Radial force due to mg is balance by the tension in the string. Where as the tangential force is an unbalanced force which tries to bring the bob to the equilibrium position.
Your force meter measures this force, which is perpendicular to the string.
 


Thanks for your help! I got it now.
 
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