Question

A coin is placed 12.0 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 39.0 rpm (revolutions per minute) is reached, at which point the coin slides off.

Answer 1

fs = m
`v^(2)` / R

= mR
`w^(2)` ........... where w = 2
`\pi`f

then fs = µsN = µs×mg = R
`w^(2)`

µs = R
`w^(2)`/g , since w = 2
`\pi`f = 2
`\pi`× 39.0

= 4.084

µs = 0.12×
`4.084^(2)` / 9.8

= 0.204

Step-by-step explanation:

when using this equation it is important to look at the units you working with so that it would be much easier to workout the solution.