# Rotational Motion and Friction

1. Sep 28, 2008

In my physics class one of the problems we have been given to solve is:

"A small button placed on a horizontal rotating platform with diameter 0.330m will revolve with the platform when it is brought up to a rotational speed of 44.0 rev/min, provided the button is a distance no more than 0.148m from the axis. What is the coefficient of static friction between the button and the platform?"

I’m almost certain that I've found the correct answer (0.008122); however, the website that I have to submit my answers into is telling me that it is incorrect. I’d appreciate it greatly if someone could guide me in the right direction. I've attached a pdf ( View attachment Physics help.pdf ) to this post showing my thought process to aid in pinpointing where I've gone wrong. Please only tell me where I've gone wrong and what I should have done; do not send me the answer. Thank you for your help.

2. Sep 28, 2008

### chislam

Looks correct, other than you forgot to convert revolutions to radians.

3. Sep 28, 2008