Let's look at an example from real life:
Each of the four turns at the Indianapolis Motor Speedway is about one quarter mile in length , and is banked at an angle of 9 degrees and 12 minutes.
What is the "optimal speed" for driving through each turn? That is, at what speed could one slide through the turn on a super-icy day, when there was no friction at all along the track?
How does that speed compare to the speed of cars during a real race? Do the cars need much of a friction force?
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