4A: Work doesn’t always have to break your back. In physics, it has a different meaning. When a force is applied to an object and results in displacement, work has been done. When an apple falls from a tree, gravity has done work on the object as it descends earthward. And as work is done by gravity on the object, its gravitational potential energy is converted into kinetic energy (which is also why it hurts as it lands on your head, hopefully resulting in a brilliant Newtonian idea). Let’s get moving!