Can someone answer a physics problem concerning static friction?

Question

A box of mass M, held in place by friction, rides on the flatbed of a truck, which is traveling with a constant speed v. The truck is traveling around in a circle on a circular roadway, having radius R. Find what condition must be satisfied by the coefficient of static friction, u, between the box and the truck bed. Express your answer in terms of v, R, and g.

Answer 1

I'm not going to give you the complete answer because you'll learn more by working through it yourself, but I'll give a few pointers.

Any object travelling in a circle at a constant speed has a centripital acceleration that can be calculated from the velocity and the radius of the circle.

Newton tells us that F[net] = ma, so the object must be experiencing a net centripetal force equal to its mass multiplied by its centripetal acceleration.

Where does this force come from? In your problem, it sounds as though the only force that could be pulling the box toward the center of the circle (the centripetal force) is the friction between the box and the bed of the truck. So, when you add up all the (horizontal) forces to get the net force, the olny one is going to be friction. F[net] = F[friction]

Now all you need to do set F[friction] equal to the F[net] that you calculated above (remember that F[net] was equal to your centripetal force), and solve for the coefficient of friction (your textbook shold have the formula for static friction, which will include the coefficient of static friction).

Good luck!

Answer 2

Static friction ??? that do not happen...