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# Energy of Falling with Air Friction

In this movie, you see a brick being dropped. Notice that at the beginning of the drop the gravitational potential energy (GPE) is equal to the total energy of the brick. As the brick falls, GPE becomes kinetic energy (KE). Once the brick is moving, the internal energy (IE) begins to increase as the brick does work on the air (heating up both the brick and the air just a little). Notice that the faster the brick is going, the more the energy becomes IE. Remember that the faster an object moves, the harder air friction pushes on the object. Newton's third law then tells us that the object must also have to push back harder on the air. Since work is force times distance, the bigger the force, the more work is done. Finally, notice that when the brick is brought to rest by the floor, all of the energy is has become internal energy. All of the energy is started with is now in the form of heat.

This simulation does not ignore the effects of air friction.