# Does marbles have friction or not?

1. Jan 4, 2012

### Carran Boey

People say that marbles experience friction when rolling across a surface,but i don't get why. The dynamic and static friction don't seem to fit here and the point is that it have a very little contact with the surface. Note that its not rubbing across the surface but rather rolling across it. You might give an example of the bowling ball,but the force used is to push it across the floor and not the kind of force to roll and ball and thus the bowling ball slides and causes friction. I really don't get why a marble experience a friction. HELP!

2. Jan 4, 2012

### Bloodthunder

If there is no friction, the marble will just slide along the surface without any rolling. Friction is what is "pulling" the bottom of the ball, causing the top of the ball to fall, which makes it roll.

3. Jan 4, 2012

### sophiecentaur

Also, when a real marble rolls on a real surface there will be a finite distortion of both surfaces - some stretching and compressing. This will involve some 'rubbing' and some energy loss - that will be 'dissipative' friction. There will also be some 'loss-less' friction which will be causing a force (analogous to a small scale version of gear teeth and more or less like what we call static friction)). But if there is no slipping / rubbing then there will be no 'force times distance' involved so no actual energy loss.
The Original Question has a number of possible answers, depending upon the depth of analysis that's required. (As usual!)

4. Jan 5, 2012

### Carran Boey

Thanks a lot! If the for the micro explanation,i would still have insisted on what i thought was right!