Machines - how they work

…

…exert five pounds of force to lift a one-pound can, but if the can is lifted one foot, the muscle only needs to contract one-fifth of a foot, a little over two inches. If the body were designed with a mechanical advantage of five, then the muscle would only have to pull with one-fifth of a pound of force, but it would have to contract five feet, and our elbows would drag across the ground.