The mechanical energy (ME) of the car is the sum of its kinetic energy (KE) and its potential energy (PE). The car's ME is determined by its initial height of the car and its initial speed (the initial speed defaults to zero). The initial potential energy (PE) is determined by the height of the start of the track, determined by the first control point of the track. Select the up and down example and then select edit track. Change the starting height of the track. What happens to the mechanical energy ME and the potential energy PE? Start the simulation by hitting the play button. How far up the other side of the track does the car get? How does the maximum height attained by the car on the right side of the track depend upon the initial height of the car? What happens to the mechanical energy when you change the initial speed?
Select the single loop example track and then select edit track. What happens to the total energy E and the potential energy PE as the initial height is changed? When the simulation is played, what happens to the motion of the car when the initial height is changed? Is there a relationship between the initial height of the car and the size of the loop when the car barely makes it around the loop?
Aerodynamic drag (friction) can be introduced by setting the drag coefficient to something other than zero. Values around .1 to .5 are good starting points. Pick one of the example tracks, set the friction coefficient to .20. What happens to the energy? When does it change the fastest? Where does the energy "go" in a real coaster? When the coaster is subject to friction, it "loses" mechanical energy ME, and the simulation tracks that loss as thermal energy TE.
You can set the coeffiecient in this simulation to a negative number. Try setting k to -.20 and run the simulation. Why is such a situation "unphysical"?
Start with the "up and down" track and then select edit track. Move the control points to create a ramp that levels out, as shown above. Play the simulation and observe the reaction force at different parts of the track. This reaction force corresponds to “how heavy the rider feels”. Change the steepness of the left side of the track and observe the changes in reaction force. Is it possible to get the reaction force to be exactly zero? What would zero reaction force feel like in the “real world”?
Change your ramp track into a fairy symmetric U shape, as shown above. Play the simulation and observe the reaction forces.
Now make the bottom part of the track narrower by moving the bottom control points closer together (as below). What happens to the reaction force?
Select the loop example track and play the simulation. Where on the loop is the reaction force greatest? Where is it the least? Now lower the starting height for the car so that the reaction force at the top of the loop is as small as you can make it. (This will have to be done by trial and error.) What would this feel like to a rider? Now adjust the starting height to be as low as possible and still have the car make it around the loop. What happens in this case to the reaction force at the top of the loop? What would this feel like to the rider, and is he glad he buckled his seat belt?