NTNUJAVA Virtual Physics LaboratoryEnjoy the fun of physics with simulations! Backup site http://enjoy.phy.ntnu.edu.tw/ntnujava/
September 28, 2020, 03:54:14 am

"Nothing in life is to be feared, it is only to be understood." ..."Marie Curie 1867-1934, Polish born French Physicist, Twice Nobel Prize Winner- Physics and Chemistry)"

 Pages: [1]   Go Down
 Author Topic: microscope view of friction force (does not depends on macroscopic area)  (Read 10236 times) 0 Members and 1 Guest are viewing this topic. Click to toggle author information(expand message area).
Fu-Kwun Hwang
Hero Member

Offline

Posts: 3085

 « Embed this message on: June 29, 2013, 06:20:50 pm » posted from:,,Satellite Provider

The following simulation try to illustrate why the friction force does not depends on macro-scopic area.
However, it does depends on microscope contact area.

The multiplication of width(w) and height(h) are kept constant. w*h=A=constant.

When the width is educed, the height increase (so the pressure increase).

A new function has been added: you can drag spring to change the external force acting on the object.

I need feedback from you! Thank you in advance!

Click the eye (image) to display the simulation

Embed a running copy of this simulation

Embed a running copy link(show simulation in a popuped window)
Full screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list
• Please feel free to post your ideas about how to use the simulation for better teaching and learning.
• Post questions to be asked to help students to think, to explore.
• Upload worksheets as attached files to share with more users.
Let's work together. We can help more users understand physics conceptually and enjoy the fun of learning physics!

 Logged
lookang
Hero Member

Offline

Posts: 1796

http://weelookang.blogspot.com

 « Embed this message Reply #1 on: August 09, 2013, 10:01:24 pm »

the link http://hyperphysics.phy-astr.gsu.edu/hbase/frict3.html has good tips on friction

Friction Assumptions

In the standard model for friction between surfaces, there are certain inherent assumptions:

1. The frictional force is independent of area of contact
2. The frictional force is independent of the velocity of motion
3. The frictional force is proportional to the normal force.

One can readily find circumstances where any or all of these assumptions are invalid, but they provide a straightforward framework for a beginning treatment of friction that satisfactorily describes many phenomena.

the applet can be include real life cases where the rule 1 is valid
and include real life case where rule 1 is not valid due to the increase in microscope contact area during broad tires on snow

http://hyperphysics.phy-astr.gsu.edu/hbase/imgmec/fnor.gif
 Logged
 Pages: [1]   Go Up
"Nothing in life is to be feared, it is only to be understood." ..."Marie Curie 1867-1934, Polish born French Physicist, Twice Nobel Prize Winner- Physics and Chemistry)"