# NTNUJAVA Virtual Physics Laboratory

## JDK1.0.2 simulations (1996-2001) => Dynamics => Topic started by: Fu-Kwun Hwang on January 29, 2004, 04:47:22 pm

Title: Frictional force
Post by: Fu-Kwun Hwang on January 29, 2004, 04:47:22 pm

A mass m1 rest on top of another mass , m2, which is connected to m3 by a light rope

(passes over a frictionless pulley).

This java applet show the force diagram and the motion of the system when the frictional forces are present.

The mass of each block is shown at the lower-right corner.
Assume the coefficients of friction between any two surfaces are the same.
Force diagram for mass m2 is shown to the left .

 Color of arrow black blue green cyan red yellow force gravity normal tension friction friction Net force on m2 source earth table rope m1 table

Click within the white area of each block to change its mass.
Click right mouse button to increase one mass unit, click left mouse button to decrease one mass unit.

Press Start will start the animation, click mouse button to suspend the animation, click it again to resume.
Press Reset for default parameters.

• Play it! and find out under what kind of condition:

1. m1 and m2 would not be accelerated? (Net force =0.)

2. m1 and m2 are accelerated together.

3. m1 and m2 are accelerated differently. (a1 a2 which one is larger?)

This is a sample gif picture.

The mass of the blocks are m1, m2,m3 , accelerations are a1, a2 , a3 .
The normal force between m1 and m2 : N12= m1 g, (where g is the gravity field strength)
so the frictional force f12 m1 gu .

The normal force between m2 and the table : N2= (m1+m2) g
so the frictional force f2 (m1+m2)gu

The tension of the rope is T.
For m1 : f12 = m1 a1
For m2:If T > ( f12+ f2 ) then T - ( f12+ f2 ) = m2 a2
otherwise f2 = T and a2= 0.

For m2: T - m3 g = m3a3

From the above equations, we can find out the accelerations.

I did that calculation already! It is your turn to do it now! O.K.
Title: topic3
Post by: on January 30, 2004, 09:03:35 am
Subject: Your Java Frictionnal Force applet.
Date: Mon, 9 Feb 1998 11:45:31 +0100
To: <hwang@phy03.phy.ntnu.edu.tw>
Thanks a lot for your on-line physics lesson.
As a french teacher i would like to ask you the permission to use your applet on a new html sheet
using french as basic language. Of course i would only translate your words( the best i can)
and leave each reference (native URL, mailto.. and comments in original state.)
The reason is that i just gave my students, (aged 17) a exam using the study of this system.
So i would like them to use your applet to get more of this study case by using new parameters
such as Mu and various masses.
This page, if possible, will be added to the site i create for my sudents (it's the very beginning),
you could surf at: http://www.chez.com/bup/index.htm and find it using french "Fichiers de TP" in the 1S section.
---- You ask for suggestions ? Of course i've got some.
*first: The masses you use : Are F1 = 10 grams or F1 = 10*g where 10 is kg and g is 9.81 mS-2 ?
(and so on for others )? case 10 grams: we use to calculate Force intensity in Newton (France) case 10 kg:
the mass seems very heavy !
*second: Some lines of your HTML page are not readable for french users because of the asian keyboard
translation,( i think.) Just above the definition table of forces, there is a line i'dont know what it is ?
(caracters like @#& and others not in use in our alphabet but for bad words ...)
The definition for f12 is quite the same it appears like: f12j[number zero]m1 g[symbol for english pound] g
I think we must read: f12 not so different of m1. Mu.g. ad so on for each reading of friction force. -----
I can make, if you look for it, other text translations, so your work to make your work used by french people.
Thanks .
Thierry Le Floch Thanks to disregard my english mistakes.
-------------------------------------------------------------------
Thierry Le Floch
UIN 4557973
Title: Re: topic3
Post by: darkego on April 20, 2009, 10:29:22 am
Dear Sir,

Thanks a lot for your on-line physics lesson.
As a student of university, i would like to ask you the permission to use your applet on a new blue-j sheet. The lesson is about frictional force. I don't understand with the code, but i wanna try to understand, because very interested for me. Would you like to help me Sir? Thanks a lot for your time.
Title: Re: Frictional force
Post by: Fu-Kwun Hwang on April 21, 2009, 06:46:27 pm
The source code is available as an attached file under the first message.
Title: Re: Frictional force
Post by: darkego on April 22, 2009, 09:23:06 am
Dear Sir,
Thanks a lot for your attention Sir. :)
Title: Re: Frictional force
Post by: janelavis on September 22, 2009, 02:58:56 pm
frictional force is a macroscopic effect of atomic size electromagnetic forses.
It usually causes the decreasion of the velocity and because of being a nonconservative force, has a path dependent integral. (I mean the work) and decreases the total energy of the body
Title: Re: Frictional force
Post by: aufche on November 05, 2009, 09:23:35 am
its must be installing java platform to running this simulations?[hide]