This is why I need to study up a lot before taking the GRE.  The velocity of the coin is (pi)*r*11/10.  I know that centripetal force is provided by friction and there is an equation that is in one of my general physics books for solving this problem without the mass of the coin, as is the immidiate obstacle.  Maybe I will get back to this later, but for now its off to Digital Electronics.

peace and physics,
Zeph

Didn't get much discussion on this one.  Hopefully more folks will participate as time goes on.  Anyway, here's how this problem works.

At the maximum radius, the static frictional force will be providing the needed centripetal acceleration.  We can therefore say

mu*N=m*omega^2*r

Because the turntable is horizontal, the normal force is equal to the weight of the coin.  We can also calculate the angular velocity, omega, from the fact that the turntable rotates at 33.3 revolutions per minute.  When we do this we find that

omega=3.487 rad/s

Putting this all together gives

mu*m*g=m*omega^2*r

Solving for r we get

r=mu*g/omega^2

Plugging in numbers gives r=0.242 m

Try not to become a man of success, but rather try to become a man of value -- Albert Einstein

I've been studying constantly this summer, all I can do is hope and pray I pass the GSE exams!! make money from home