You put three identical coins on a turntable at different distances from the centre and then turn the motor on. As the turntable speeds up, the outermost coin slides off first, followed by the one at the middle distance, and, finally, when the turntable is going the fastest, the innermost one. Why is this?

Options

A. For greater distances from the centre the centripetal acceleration is higher, and so the force of friction becomes unable to hold the coin in place.
B. The weight of the coin causes the turntable to flex downward, so the coin nearest the edge falls off first.
C. Because of the way the turntable is made, the coefficient of static friction decreases with distance from the centre.
D. For smaller distances from the centre, the centripetal acceleration is higher.

Answer

A

Explanation

`a_(c) = omega^(2) r and f_(ext) = m omega^(2) r`