090315 Kinmodel lab

course phy202

David,I believe I'm somewhat lost on the starting of this lab but below will be my observations.

* 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?).

The red speed appears to be the second counting number at the top of the line. As far as trying to estimate the number of collisions that's going to be a wild guess. With the counter counting about 1.5 sec before resetting and watching the left number change for each collision I saw numbers between 2 and 10 for 1.5 sec intervals so let's say we had about 6 collisions per 1.5 sec so the avg time between collisions might be 1.5/6 = .25 sec per collision

* Watch the 'blue' particle, and speculate on what property of this particle is different from that of the other particles.

The blue particle appears to move slower overall than the other particles.

* Watch as the 'red' particle sometimes turns yellow. What causes this? What property does the particle have when it is yellow?

I never saw the red particle turn yellow. If I was to speculate it might be an increase in velocity after getting hit by another particle and our eyesight recognized the abnormally as a yellow color.

* What might the graphs represented at the right of the screen represent?

This is another question I'm unsure of. Only speculating and from the introduction information I believe it has something to do with the KE of the red and blue particles at a given time. If the particle hit directly at the top at full velocity the KE would be the greatest at that given time on the scan time and would indicate the graph of higher energy conversely the bottom of the graph being hit would indicate a lower KE and lower energy

The 'blue' particle tends to move more slowly and to have less velocity change in a collision than a 'red' particle. This indicates that its mass is greater than that of a 'red' particle.

The graphs depict frequency distributions for the kinetic energies of a typical particle, and for the speeds of a typical particle. The frequency distribution rises to a peak then approaches the horizontal axis as an asymptote, indicating that the most frequently observed velocities are those a little below the midrange of observed velocities (e.g., around 5 on the velocity scale of the program), and that increasingly higher velocityes are less frequent, as are progressively lower velocities.

The difference between the velocity and KE distributions is subtle; since KE involves squared velocities, the KE distribution will exhibit greater concavity.