Question

enumerate the nature of the force which may be omitted in forming the equation of virtual work

Answer 1

The forces which may be omitted in forming the equation of virtual work are:

1. Forces applied to fixed points (ds = 0).

2. Forces acting in a dirn normal to the disp (cosα = 0).

3. Reaction at a frictionless pin due to rotation of a body around the pin.

4. Reaction at a frictionless surface due to motion of a body along the surface.

5. Weight of a body with cg moving horizontally.

6. Friction force on a wheel moving without slipping.

The sum of work done by several forces may be zero:

1. Bodies connected by a frictionless pin.

2. Bodies connected by an inextensible cord.

3. Internal forces holding together parts of a rigid body.