A simple machine is a device that changes the magnitude and/or direction of force. The six classical simple machines are the lever, the wedge, the screw, the inclined plane, the pulley and the wheel and axle. A complex machine is made from a combination of these six simple machines in order to perform more complex tasks. Simple machines rely on both the principle of force and the principle of torque in order to achieve their desired results.
Glue the safety clip to one end of the rope so you can fasten your rope to various objects.
Have a volunteer hold the pulley stationary in the air as you wrap the rope around it. Clip one end of the rope to a chair or other object, and pull on the other end of the rope. The effort it takes to move the chair shows how force on your end of the rope is redirected to pull the object directly toward the pulley.
Wrap the rope around two pulleys, showing how the pulleys can be compounded to redirect the force twice.
- cistern pulley image by JCVStock from Fotolia.com