(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A uniform metre rule of mass 100 g is supported by a knife-edge at the 40 cm mark and a string at the 100 cm mark. The string passes round a frictionless pulley and carries a mass of 20 g as shown in the diagram.

At which mark on the rule must a 50 g mass be suspended so that the rule balances?

2. Relevant equations

3. The attempt at a solution

using the [tex]\sum F[/tex]=0

therefore, R at the knife-edge + T at the 100 cm = W

R = 0.8

then take the moment at the c.g, which is at 0.5

therefore R(z)=T(50)

in the end,what i got is z=0.3125

where T=0.5N

wrong again....

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# Homework Help: Moments of force

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