Maximum Static Friction Force for Spinning Disk and Block System

[splac6996]

Homework Statement

A penny of mass 3.10g rests on a small 20.0g block supported by a spinning disk. The coefficients of friciton between block and disk are .750(static) and 0.640(kinetic) while those for the penny and block are 0.520(static) and .450(kinetic). What is the maximum rate of rotation in revolutions per minute that the dsk can have, without the block or penny sliding on the disk?

Homework Equations

The Attempt at a Solution

 

[Doc Al]

What force prevents the penny from sliding?

 

[splac6996]

static friction

 

[splac6996]

I think I can solve this problem now thanks

 

[Doc Al]

Right. So what's the maximum force that static friction can exert on each object?