Roller Coaster Physics

## Question:

Hello Mr. Jones,
Got some questions while doing my Physics project on "Roller Coasters".

Q1:
Why shouldn't be the loop of real roller coasters be round in shape? Why must it be elliptical in order not to hurt the riders?

Q2:
Must the starting point be higher then the top of the loop, so that there is enough energy for the coaster to complete it?

Q3:
Is there any factors limiting the no. of carts in a coaster train?

## Answer:

Concerning question #1
I am not aware of any reason why the loop in a roller coaster could not have a circular projection. Of course it can not be a simple circle but actually must a spiral so that the cars have a means of entering and leaving the loop. If you learn why an elliptical shape is required, please let me know. I am still learning new physics all the time.

Concerning question #2.
This is my shortest answer ever. Yes.

About question #3.
One obvious limitation is that the train of cars must be shorter than the total roller coaster track. It is also best to have the train short compared to the size of any of the features (hills, curves loops, etc) of the track so that the changes in acceleration which cause the excitement are not moderated by having part of the train rising while another part is falling. I suspect a more restrictive limiting factor is keeping the total mass of the train to a minimum to limit the forces induced by the accelerations the train experiences.

I wish you Happy Lunar New Year & Kung Hei Fat Choi as well.

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JDJ