Question

A uniform half metre rule is balanced horizontally across a knife edge placed 20cm from A. A mass of 22.5g is hung from end A.
1. What is the mass of the rule
2. What is the force exerted on the rule by the knife edge?
bobpursley
assume the mass of the rule is at the 50 cm mark.

massrule*(50-20)=22.5g*20
solve for massrule

force on knife edge=20+massrule
1000g_1kg
22.5g_x
x_22.5g^1kg/1000g
m_0.0225kg
half of meter rules is 50 cm
from point A to pivot = 20 cm and rest part is 30 cm
by using law of lever we get
20 cm*22.5 g= 30 cm * mass of the rule
mass of the rule = 15 g
b) force = to the weight then F= 15*9.81
This is not my question

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