Ok have a look at the diagram below(adsbygoogle = window.adsbygoogle || []).push({});

A bob of mass m is on the inside of a funnel. The funnel is rotating with an angular velocity omega. The walls of the funnel has a friction coefficient of mu

The question is Show that there is an angle theta = theta max for which the bob cannot slide upwards if theta > theta max no matter how large the omega is. Determine theta max

So far here's what i have

force equation in the X direction (masses cancel out)

[tex] \omega^2 r cos \theta = \mu g cos \theta + \mu \omega^2 r sin \theta + g sin \theta [/tex]

teh answer is [tex] \frac{1}{\mu} = tan \theta _{max} [/tex]

seems to be derived by taking some limit as omega approaches a large number then the g sin theta nad the g cos theta part becomes negligbile. But i want to understand why this is being done. Any help would be greatly appreciated!!!

**Physics Forums | Science Articles, Homework Help, Discussion**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Centripetal Acceleration

**Physics Forums | Science Articles, Homework Help, Discussion**