# Finding the coefficent of static friction

1. Nov 11, 2008

### pinkerpikachu

1. What is the minimum coefficient of static friction required for a roller-coaster car to complete a circular loop of radius r, if it is traveling with sufficient speed v?

I'm just very confused with all of this because the question seems so broad and there are so many things to consider.

A little bump or nudge in the right direction is highly appreciated.

Also I don't really know what kind of things I am supposed to assume besides the weight of the rollercoaster car, the velocity, and the radius. Is that sufficient information?

Help is highly appreciated!

Last edited: Nov 11, 2008
2. Nov 11, 2008

### Staff: Mentor

I don't understand the question. Are you presenting it word for word exactly as it was given?

3. Nov 11, 2008

### pinkerpikachu

Yes, that is word for word.

It means (these are all values off the top of my head), assuming the weight for a rollercoaster car is about 1000 kg, it is going at a speed 40 m/s around a loop with radius r= 100m what is the minimum coefficient of static friction that the wheels must have for the car to be able to complete the loop.

I though it should be a kinetic friction at first, but i remembered that what allows a wheel to turn is all static friction

4. Nov 11, 2008

### Staff: Mentor

Sorry, but the question still makes no sense to me. You can make the coefficient of friction zero for all it matters, let the wheels slide instead of roll.

(Is this from a textbook, by any chance? Or one made up by your professor?)

5. Nov 11, 2008

### pinkerpikachu

its one by my professor.

hm...sorry I can't make you understand it.

one more try:

There is a rollercoaster car, it order for it to complete a loop its wheels have to have a certain static friction coefficient at a certain velocity. Taking into count all of the forces on the coaster, what is the coefficent of static friction?

Thanks for trying.