- From: Simon Erskine
- Date: 17 April 1999
*Subject: Three forces in equilibrium*
A particle has a mass 125grams and hangs on a string. The particle is pulled aside by a force of 0.75N so that the string makes In what direction is the force applied? There are two possible answers. |

As the diagram shows, we have three forces acting at a point which are in equilibrium.

This is an ideal situation to use Lami's Theorem, which is based on the sine rule.

Taking the second and third terms gives:

And with *g* = 9.8:

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