School and Work

The coefficient of static friction between a small coin and the surface of a turntable is 0.30. The turntable rotates at 33.3 revolutions per minute. What is the maximum distance from the center of the turntable at which the coin will not slide?
(A) 0.024 m
(B) 0.048 m
(C) 0.121 m
(D) 0.242 m
(E) 0.484 m

answer with explanation are welcome. thanks in advance.

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When you go to sleep each night in the comfort of your overstuffed mattress. Do you fall out of bed or through the mattress? Nope. In fact you just lie there like a lump of coal. That's static equilibrium.

It's static because you're not moving; lumps of coal rarely do. It's equilibrium because you are not accelerating; so all the forces acting on your tired old body add up to zero...in math talk F = SUM(f) = ma = 0 where m is your mass (put on a little weight have we?).

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They aren't really any different. Just different aspects of the same subject that we study.

"static electricity" or electrostatics is studying charge situations whereby all systems are in ELECTROSTATIC EQUILIBRIUM. That is, they aren't really actively doing any re-distribution.

"Current electricity" is what you shouldn't call it. You should just call it circuits. That is when we focus a study on an application of when electrostatic equilibrium ISN'T the case, and the results are interesting to us.
http://amasci.com/miscon/eleca.html#statcur

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