# Summary

The equations of equilibrium involve summing forces and applied moments on a structure. The summation must total zero for the structure to be in equilibrium. This is used to solve mathematically for the reactions that act on a structure.

- All structures must satisfy equilibrium if they are to fulfil their function of carrying loads. This

means,

2. An applied moment is the produce of a force and the perpendicular distance from the reaction to the line of action of that force.

3. A force is positive if it acts in the positive axis direction. An applied moment is positive if it follows the right hand screw rule when your thumb is in the positive axis direction.

- Practice Problems:
- Hibbeler, R.C., Statics and mechanics of Materials, Problems 2-14 & 4-1.