In a wrench, almost the entire length is the effort arm, so there is a great deal of mechanical advantage, and the longer the length, the more MA there is. When you apply force to the handle of the wrench, the load end moves. If you double the length of the wrench (effort arm), you have halved the required force to do the same amount of work, because work = force x distance. Chances are, if you really are having a hard time loosening a bolt, you don’t want the same amount of work; you want more work so the bolt comes loose! If you increase the distance and use the same amount of force you were using with a short wrench, you’ve now increased the work, because the mechanical advantage is greater. Do you see how this simple equation can tell you a lot? This is probably one of the most visible and practical examples of physics in use!
