"They may look different, be vastly different in scale, and have different purposes, but when seen in terms of principles, they work in the same way." (page 8)

"Every object on Earth is held together and in place by three basic kinds of force; virtually all machines make use of only two of them." (page 9)

"Underlying the actions of all machines is one principle which encompasses all the others— the conservation of energy.. This is not about saving energy, but about what happens to energy when it is used. It holds that you can only get as much energy out of a machine as you put into it in the first place—no more, no less." (page 9)

"Work has two aspects to it: the effort that you put in, and the distance over which you maintain the effort. If the effort increases, the distance must decrease, and...