# Rolling motion

1. Oct 27, 2005

### ambuj123

Hello
well i have a very basic doubt
well when we have a rolling motion
and surface is rough
then what i used to do was write linear and translation equation and find f (Frictional force)
Now is this frictional force same as static friction and can we write is as kmg where k is coeffecient of static friction assuming since point of contact is at rest so static friction acts.
further if friction acts during rolling motion we know energy remains conserved and no dissipation takes place but does that mean frictional force does no work
thanx

2. Oct 27, 2005

### Gokul43201

Staff Emeritus
There's a different constant known as the coefficient of rolling friction, which is what you must apply.

http://webphysics.davidson.edu/faculty/dmb/PY430/Friction/rolling.html [Broken]

Last edited by a moderator: May 2, 2017
3. Oct 27, 2005

### siddharth

During rolling without slipping, the point of contact is instantaneously at rest. So when an object rolls without slipping on a surface, the friction acting corresponds to static fricton.
Since the point of contact is instantaneously at rest, the friction force does not act over any distance and therefore does not change the total energy.
Also, the maximum possible force by static friction is given by kN. So, in most questions, where it is only mentioned that sufficient friction to prevent slipping exists, you can't use the static friction as kN.