Thread: Wheel Confusion
View Single Post
  #5   Spotlight this post!  
Unread 04-01-2009, 21:06
Matt H. Matt H. is offline
Long Distance Mentor
FRC #1726 (N.E.R.D.S.)
Team Role: Alumni
 
Join Date: May 2006
Rookie Year: 2007
Location: Sierra Vista, AZ
Posts: 238
Matt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond reputeMatt H. has a reputation beyond repute
Re: help me please

Quote:
What does 0.06 mean? 0.00 means there is no friction at all, 1.00 means they are solidly locked (maybe glued together?). Anything in between is how much they can slip, or more accurately how easily they can slip against each other. This Coefficient of Friction is denoted by the greek letter Mu.

A rubber tire against dry pavement has a Mu of maybe 0.8 or 0.9
That same tire has a Mu of about 0.1 or 0.2 on smooth ice.
A spiked golf shoe has a mu close to 1.00 on carpet.

Does that help?
Don,
That's really not a correct description of friction. A Mu of 1.00 does not mean two surfaces are solidly locked together. There is no limitation that mu must be between 0-1. In fact many object pairs have a mu greater than 1.00. Mu is a dimensionless constant found by comparing the downward force on an object to the force resisting its motion. For example in you have a 120 lb robot a mu of .05 means only the wheels can exert 6 lbs of forward force using friction before they being to slip. If the wheels have a mu of 1.5 then the robot can exert 180 of pounds of force using a frictional connection to the ground before slipping.

A real world example of a mu higher than one would be copper on copper 1.3 silver on silver 1.5 etc. source: http://www.engineershandbook.com/Tab...efficients.htm
Reply With Quote