A coin is placed 17.0 cm from the axis of a rotating turntable of variable speed. When the speed of the turntable is slowly increased, the coin remains fixed on the turntable until a rate of 26.0 rpm (revolutions per minute) is reached, at which point the coin slides off. What is the coefficient of static friction between the coin and the turntable?

The coefficient of static friction between the coin and the turntable is 0.13.

Explanation:

As we know that,

   Centripetal force = static frictional force

or,  

     v =

or,   ......... (1)

Here, it is given that

       r = 17 cm,       = 26 rpm,    

and  v = ..........(2)

Putting equation (2) in equation (1) we get the following.

            =

            = 0.128

            = 0.13 (approx)

Thus, we can conclude that the coefficient of static friction between the coin and the turntable is 0.13.

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )