course Phy 202
6/10 8pm
Preliminary ObservationRun the program kinmodel, accepting all defaults by using the 'Enter' key to answer the prompts on your computer (the computer will then automatically pick the selection with the asterisk) and observe the particles or 'billiard balls' bouncing around the screen and off one another.
• Watch the KEx and KEy values as they change with each collision, representing the total x and y kinetic energies of the particles.
• Watch the 'red' particle for a couple of minutes, estimating the average time between its collisions and its average speed (one of the speeds given near the top of the screen corresponds to that of the 'red' particle--which is it?).
• Watch the 'blue' particle, and speculate on what property of this particle is different from that of the other particles.
• Watch as the 'red' particle sometimes turns yellow. What causes this? What property does the particle have when it is yellow?
• What might the graphs represented at the right of the screen represent?
• Strike the 'S' key to stop the simulation, and if you are done give the appropriate response to the prompt to quit the program. CTRL-ALT-DELETE will also stop the program, but if you're not careful it will reboot your computer so avoid that option if you can.
Before reading further email your instructor with your best answers to these questions. There are two good reasons for not reading ahead: If you get your answers by reading ahead your instructor will be able to tell, and if you read ahead you won't learn as much.
Responses:
The speed for the red particle appears to be the first of the “speeds of last 2 molecules”. I estimate that on average the red particle collides about every 20 time units, and its average speed is about 5.
The blue particle appears to have less kinetic energy than the other particles, probably due to its mass, because I don’t see its speed (the last number in the “speeds of last 2 molecules” getting very high.
The red particle appears to turn yellow when it collides with another particle and its speed reaches at least 8.
I think the graphs on the right might represent the speeds and collisions of the red particle vs. time.
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&#Good responses. Let me know if you have questions. &#
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