The following are all examples of internal forces except...

The following are all examples of external forces except...

A structure is ready to be used in real life once...

Which of the following is a simple machine?

An axe is an example of which simple machine?

A third class lever...

Which of the following is an example of a first class lever?

A pulley can be used to...

The actual effect of a force on a structure depends on the magnitude, or size, of the force, the direction and the location where the force is applied.

External forces such as extreme weather pose a constant threat to the structural reliability of structures. 

The two main types of forces are static and dynamic forces.

Internal forces resist the external forces acting on a structure. 

In order to maintain structural reliability the external forces must be greater than the internal forces. 

A force is

Complex machines are

A static load is

Gravity is a force caused by the earth pulling objects toward its centre.

Torsion is 

Compression is

Simple machines make it harder to move a load.