Recent content by jason.farnon

I was using F to refer to the "rolling friction". Why does that affect the derivation? The translational effect on the centroid of the wheel/ball/object should be analyzable separately from the spinning wheel, shouldn't it? I have encountered derivations where that appears to be the case.

Thanks, that is something I was wondering about. But, maybe I'm missing something, but I don't see that it answers my original question. Take the point that there is only rolling friction and thereafter. I don't see what is wrong with my two derivations for the acceleration of the ball, but they...

I don't follow. If friction were zero it seems to me there would be no rolling at all. The object would just slide.

right, no one is pushing it, but there is friction. sorry if I was unclear in setting up the problem. Say I take a wheel, cylinder, ball or whatever and set it rolling on the ground, as you might pitch a bowling ball. It has a certain initial velocity but I am no longer pushing it. Friction is...

What is the force applied you're referring to? I was referring to the situation after the person/external agent releases the wheel with some initial velocity, and the wheel is just rolling by itself on the ground without slipping subject to friction.

Homework Statement I think I have too many equations for unknowns for rolling without slipping. Suppose a wheel is pushed and left rolling along the ground without slipping. Homework Equations T = I*alpha, where alpha is the rotation about the wheel's centroid and I is the moment of...

I don't personally. I just interpret the definition of friction as requiring it. Perhaps a related question I have had. In the usual example of a block resting on an incline, with gravity, the normal force is less than the weight. The component of the weight perpendicular to the incline alone...

yes I guess it is, at the point of tangency. Then I still don't see why there is a tendency to move in the outward radial direction, which is needed for friction to act inward? What is the relevance of the wheels continuing to roll at an angle at the same speed, if friction is "turned off"...

I was wondering, if friction is centripetal and if friction opposes motion that is opposite the motion that would occur in its absence, what is that outward motion. I think we may be agreed it is just the tangential motion being opposed. Let's say I have a switch that can make friction on the...

Hi Tiny-tim, Thanks I had not even considered the difference between rolling and sliding. But I am still not clear. You mean no additional power, after whatever gives the car an initial velocity? I can visualize that, e.g., a satellite rotating around a planet, where gravity replaces the...

PeterO, Thanks for the explanation and examples. I think you got me close but not quite there. I can see the operation of friction in your briefcase on a train example. In the absence of friction the briefcase moves to the back of the train relative to the train's motion, so the direction of...

Sorry for not following the template, this is a follow up to a few other old posts. In solutions to problems where a car negotiates an unbanked turn, I usually see that the centripetal force is supplied by friction. My understanding is that friction applies in the direction opposite motion...