Describe three machines that humans have designed and explain how the mechanical advantage is used.

The three machines that the human can used for designed is wheel axle, lever, inclined plane etc, ...

Explanation:

These are the machine transmits only the mechanical energy. mechanical energy is gives the mechanical advantage. The mechanical energy is the ratio of the force by the machine to the force applied on the machine.

Under the mechanical energy, the distance from the load to the applied. The mechanical energy of the machine is more than the force to the machine can give output.