Pendulum measuring the restorative force HELP

[milk242]

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

F_g= -mg
(F_g)_r = -mgcos(theta)
(F_g)_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.

 

[rl.bhat]

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.

 

[milk242]

Thanks for your help! I got it now.