Uni Stuff > Physics
umep physics thread
/0:
But the problem is if you take the pivot as the centre, then how do you find the magnitude of the frictional force? The gravitational force comes easily as ... but what is the expression for friction?
evaporade:
what is the ratio of its final centre-of-mass velocity compared to a hollow cylinder rolling down a hill with friction?
Sqrt2 : 1
dcc:
--- Quote from: /0 on June 16, 2009, 06:02:13 pm ---But the problem is if you take the pivot as the centre, then how do you find the magnitude of the frictional force? The gravitational force comes easily as ... but what is the expression for friction?
--- End quote ---
Who says there'll even be a torque at all, without friction? With friction, its clear to see that the torque being applied is proportional to the normal force (and hence the gravitational force), but without friction, that torque isn't there to turn the object.
The gravitational force on this object (assuming its nice and circular/cylinderish) will act on the centre of mass, and hence will not apply a torque to the object (Think about it, if you have a plank in a gravitational field, the torques on the left of the plank will 'even out' with the torques on the right, so there will be no net torque).
At least, that's what I think it is. This could be wrong, but that's what I would have written if someone asked me :P
/0:
Yeah lol I guess you're right, thanks guys :D
evaporade:
what is the expression for friction?
1/2 mgsin@
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version