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A balance is a tool for measuring the mass of a body by comparing its weight against that of a set of weights whose mass is known.



The balance consists of two arms.

These are the two halves of a rigid rod placed on the fulcrum such that the arms are of the same length.

In the above diagram, both arms are of length $d$.


The fulcrum of the balance is a fixed point upon which the arms rest, and upon which they are free to pivot.


At the end of each of the two arms of the balance is a pan.

Into one of these pans the body is placed which is being weighed.

Into the other pan, the user is to place exactly the weights which will cause the arms to be horizontal.

Also known as

A balance is also known as a balance scales or a (set of) scales.

While common and colloquial, the word scales is a misnomer, as such a machine tends not to have a scale as such.

Also see

  • Results about balances can be found here.