Projects: UDL : UDL Friction Activity 5-6 Halt
This page last changed on Oct 18, 2007 by ehazzard.
When an object slows down, where does the energy go?
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In the picture of the airplane coming to a stop on the runway, smoke is pouring off the front wheel. Why? Where is all the heat coming from?
Cars, trucks, and railroad trains all use brakes to slow down. In order to stop, they must give up all of their energy of motion - the same energy it took to get them moving! How do brakes use up that energy?
Here is a model of a surface with different amounts of friction. The "Push it" button gives the object a shove that starts it with a fixed speed. You can choose different amounts of friction – steel, wood, or carpet.
The graph show three values:
Run the model with steel.
Describe the graph of kinetic energy (black line).
Describe the graph of heat energy (red line). What did it do as the object slowed down?
You probably observed that the kinetic energy graph goes down and the heat energy graph goes up as the object slows down. Why do you think this happens?
How is the graph the same as for steel? How is it different?
How is the graph the same as for wood? How is it different?
If you added the kinetic energy and the heat energy together, what would be the result?
a. The sum would get smaller.
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