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course Phy 231
3/25 10pm
On the collision simulation, one thing that's taking me a while to understand is the
If I'm understanding it correctly, that's the point at which, if the two masses were on a see-saw, the fulcrum would need to be to achieve equilibrium.
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The center of mass is indeed the point at which the two masses would balance. In some cases the center of mass will remain stationary; in that case you are said to be viewing the collision from the center-of-mass frame. More typically the center of mass will be moving.
The center of mass frame is particularly useful in analyzing perfectly elastic collisions. In that case the two velocities simply reverse upon collision.
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When I switch to 1-dimension, this is easier to predict (when I turn it on and off and see if I can estimate where it will be when I click it back on).
Keeping it in 1 dimension for a while, I varied the elasticity. Lowering it seems to accelerate the rate at which kinetic energy decreases. I'm assuming that it's tracking KE for the entire system.
Is the reason KE decreases because KE is lost in the collision? Would that mean that the work the objects do on each other during the collision is on a nonconservative force?
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That is correct. Only in a complely elastic collision are the forces conservative, so that KE remains unchanged (see also my preceding not regarding elastic collisions).
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Adding a third object shows pretty clearly how each collision actually appears to transfer KE from one object to another.
What I really don't understand is how it shows KE of 0.00J when objects are still moving. My guess is that it just means KE is less than 0.01J, but not really 0."
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This likely means that the KE rounds to 0, which is pretty much what you said.
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