rolling & slipping


by dev70
Tags: rolling, slipping
dev70
dev70 is offline
#1
Jan11-13, 02:33 AM
P: 58
hi pf, the more i think i have understood classical rotational mechanics the more it turns out to be clumsy? i am just not able to understand the slipping and rolling of bodies? somewhere friction comes into play and somewhere dont?
"if a body rolls without slipping such that velocity of COM doesnt change then no frictional force acts on the body" how? why would a body roll if there is no friction?

please help me out. i am tired of reading so many books. still not able to solve numerical related to it
Phys.Org News Partner Physics news on Phys.org
Physicists design quantum switches which can be activated by single photons
'Dressed' laser aimed at clouds may be key to inducing rain, lightning
Higher-order nonlinear optical processes observed using the SACLA X-ray free-electron laser
A.T.
A.T. is online now
#2
Jan11-13, 02:51 AM
P: 3,546
Quote Quote by dev70 View Post
why would a body roll if there is no friction?
It's not about how it started rolling. Once it is rolling at constant speed no friction is necessary.
CWatters
CWatters is offline
#3
Jan11-13, 06:19 AM
P: 2,861
What AT said.

It actually says that in the quote...

"if a body rolls without slipping such that velocity of COM doesnt change then no frictional force acts on the body"
Consider a train that has solid steel wheels (so negligible rolling resistance).... When it accelerates it applies a force on the track in one direction, when it brakes it applies a force in the opposite direction. When it does neither and travels at a constant velocity no frictional forces are acting.

Aside: In a real train this isn't true because of things like wind resistance and rolling resistance isn't totally zero. So some force (and power from the engine) is required to maintain a constant velocity.

dev70
dev70 is offline
#4
Jan11-13, 12:36 PM
P: 58

rolling & slipping


ok..if i consider a sphere rolling as well as sliding down an inclined plane? what should i interpret? friction is acting or not?
Doc Al
Doc Al is online now
#5
Jan11-13, 12:48 PM
Mentor
Doc Al's Avatar
P: 40,889
Quote Quote by dev70 View Post
ok..if i consider a sphere rolling as well as sliding down an inclined plane? what should i interpret? friction is acting or not?
If the sphere is rolling without slipping down the incline then there must be a friction force to produce the angular acceleration.


Register to reply

Related Discussions
Confusion over Rolling with Friction and Rolling Without Slipping Introductory Physics Homework 16
Cylinder rolling up inclined plane - Rolling without slipping Introductory Physics Homework 15
rolling without slipping Introductory Physics Homework 3
Minimum Angular Speed to start SLIPPING BEFORE ROLLING WITHOUT SLIPPING Introductory Physics Homework 1
Rolling without slipping help Introductory Physics Homework 2