Beads sliding on a rotating hoop

[newcool]

Thanks for the help

 

[learningphysics]

Consider this problem:

http://www.physics.harvard.edu/probweek/prob35.pdf

The solution is here:

http://www.physics.harvard.edu/probweek/sol35.pdf


Why is N and $$mg *\cos\theta$$both positive? I thought N point away from the hoop

No N is inward. The beads try to go outward, but the loop pulls them inward.

 

[newcool]

Thanks, I got the first part, anyone have any idea bout the second?

 

[learningphysics]

Thanks, I got the first part, anyone have any idea bout the second?

Yes, the second part looks right to me.