A machine is any device used to change the magnitude or direction of an applied force. It is used to make tasks easier and less force-needing for humans, by transferring energy from one point to another. It’s main advantage is that it enables a person to exert a force greater than could be exerted by using muscles alone, or to apply a force more efficiently, as with the pulley. Machines don’t always have …showed first 75 words of 1520 total…

…showed last 75 words of 1520 total…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.