# Centrifugal force coins

Two coins are on a turntable that steadily speeds up, starting from rest, with a ccw rotation. Which coin flies off the turntable first?

Coin 2 is further away than coin 1.

MY ATTEMPT:

I believe centrifugal acceleration is done by friction. So fs=us*m*g. Fc=mv^2/r.

Then, v=sqroot(us*g*r).

Suppose coin 2 is at radius 2(r1), (r1) being the distance from center of coin 1.

angular velocity 1= r1(sqroot(us*g))

angular velocity 2=2r1(sqroot(us*g))

So, I conclude that coin 1 must be thrown off first. HOWEVER, the answer manual says it is coin 2, which is an obvious answer for me too. But, I can’t seem to be able to prove it.

http://ift.tt/MZNWvK

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