Levers, gears, incline planes, pulleys, and hydraulic lifts, are known as simple machines; they make make heavy lifting/pulling much easier. This tends to lead many students to think that they somehow produce energy. Have them conduct the exercises described in the text such that they discover that this is not the case. Such simple machines only provide “mechanical advantage”. (Mechanical advantage is the ratio of the force that performs the useful work to the force that is applied.) Yes, less force needs to be applied but the hooker is: That lesser force must be applied over a longer distance such that the work input (force times distance) equals the the output performed by the machine. See the following examples and please post any questions or comments.