#### Sample problem:

A uniform beam *AB* of mass *M* and length *L* is hinged to a smooth wall at *A*. It is supported by a light stay *CD*, which joins at point *C* on the beam to a point *D* on the wall (see Fig. 1). If the beam carries a mass 5*M* at *B* find the thrust in *CD* and the magnitude and direction of the reaction at *A*.

#### Solution

In Fig. 2 we identify and illustrate the forces acting in the system so we can build a mathematical model to simulate the beam arrangement:

The forces acting on the members are:

*X* = horizontal component of reaction at hinge *A*

*Y* = vertical component of the reaction at hinge *A*

*T* = thrust on *CD*

Take moments about *A* for *AB*: