37_work_energy

37_work_energy - Lesson 37: Work & Energy The everyday...

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Lesson 37: Work & Energy The everyday definition of “work” and the one that we use in physics are quite different from each other. When most people think about “work” they think of the job that they have. Although it is possible that a person might be doing the physics definition of work while at his or her job, it is not always the case. Like so many other things in physics we have to use an exact definition to really explain what work is. In fact, we have to use two definitions of work. Definition 1: Work is a transfer of energy. This is probably the most basic definition possible, but it still has many ways of being interpreted. Let's say you are running up some stairs when you trip and fall back down the stairs. At first the chemical potential energy in your muscles was being converted into kinetic energy as you moved and gravitational potential energy of being higher up. When you fell, the gravitational potential energy of being high up changed into kinetic energy as you fell faster and faster down the stairs. In both cases, work was happening because energy was changing forms. This definition of work can also mean that energy is transferred from one object to another object. Definition 2: Work happens when a force causes an object to move through a displacement. Be careful with this definition. Some people incorrectly assume that it means a force is work. Instead, what it really means is that a force exerted on an object can cause work to happen. We have to be careful that the object actually has a displacement, otherwise work has not happened. The other detail for this definition is that the force and the displacement must point in the exact same direction. Example 1
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37_work_energy - Lesson 37: Work & Energy The everyday...

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