A balanced lever has two weights on it, the first with mass 6 kg 6kg and the second with mass 45 kg45kg. If the first weight is 9 m9m from the fulcrum, how far is the second weight from the fulcrum?

1 Answer
Jan 19, 2016

d=1.2md=1.2m

Explanation:

A body which has no tendency to rotate under the combined result of a number of forces acting on it is called to be a balanced state.

The rotational tendency of a force is called Moment of the force.

Moment ==Force times ×Distance=F times D=F×D

where DD is the length of Moment arm, which is perpendicular distance between the line of action of the force and the center of moments.

Also in a balanced lever clockwise moments are equal to clockwise moments.

In the given question, forces acting are two weights for which
F=m.gF=m.g where gg is acceleration due to gravity.

If dd is the length of Moment arm, i.e ., perpendicular distance between the weight and the fulcrum, then moment of one force about the fulcrum is equal and opposite to the moment of other force about the fulcrum.

Stating mathematically
Moment_1=Moment_2Moment1=Moment2

or m_1.g.d_1=m_2.g.d_2m1.g.d1=m2.g.d2
implies m_1.d_1=m_2.d_2m1.d1=m2.d2

Inserting given values
6 times 9=45.d_26×9=45.d2
or d_2=(6 times 9)/45 md2=6×945m