Author Topic: Pulley  (Read 231381 times)

Fu-Kwun Hwang

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Pulley
« on: January 29, 2004, 06:06:40 pm »
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 This java applet shows the advantage of a pulley.
 1. There are three sets of pulley.
 2. Double click within those block to change its mass.
    Right click to increase one unit(gravity g).
     Left click to decrease one unit. Mass of those block are shown in blue.

 3. You can click within those block and drag it up and down.
 4. Gravity pulls down one the block with force Mg.
    The rope pulls up on the block with force T(value shown in red).
     If the total force acting on the block is zero, it is in equilibrium.
     Otherwise, the block is under acceleration(animation starts).
      The animation is paused while you press the mouse button.




    Harry the painter swings year after year from his bosun's chair.
     His weight is 500N and the rope, unknown to him, has a breaking point of 400N.
     Why doesn't the rope break when he is supported as shown to the left on the above picture?
     One day Harry is painting near a flagpole, and,
      for a change he ties the free end of the rope to the flagpole instead of to his chair as shown to the right.

    Why did Harry end up taking his vacation early? (Not really funny! Too bad!)


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topic8
« Reply #1 on: January 30, 2004, 08:45:45 am »
Subject: pulley applet
Date: Fri, 26 Sep 1997 09:21:00 -0400
From: "Robert B. Muir" <bob_muir@uncg.edu>
Organization: Physics & Astronomy, UNC Greensboro
To: hwang@phy.ntnu.edu.tw, bob_muir@uncg.edu
You have done a very good job developing these wonderful applets.¡@
I have not run all of them yet, but look forward to doing so.
I just tried the Pulley applet and had a problem.¡@
It seemed to download, but nothing ever appeared in the display area.¡@
The text below the display area looked ok.¡@
I am running Netscape Communicator 4.01 on a 166 MHz Pentium with 30 Mb of Ram.¡@
All the other applets I have tried worked ok.
Thank you for making this material available to us all.
Sincerely yours, Bob Muir
Physics & Astronomy
U North Carolina at Greensboro
Greensboro, NC USA

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topic8
« Reply #2 on: January 30, 2004, 08:58:10 am »
Subject: Pulley Experiment
Date: Sun, 25 Jan 1998 13:14:53 -0600
From: "Radim Kolarsky" <rljc@worldnet.att.net>
To: <hwang@phy.ntnu.edu.tw>
Dear Dr. Hwang:
My son and I have enjoyed visiting your site today and yesterday, looking at your experiments.
In an effort to assembe information for my son's school science project,
we attempted to see the "Pulley" page but, unfortunately, the link is broken.
I have marked your site among my bookmarks and will definitely come visit again.
Sincerely,
Radim A. Kolarsky

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topic8
« Reply #3 on: January 30, 2004, 08:58:32 am »
Subject: Pulley and more...
Date: Mon, 26 Jan 1998 20:57:05 -0600
From: "Radim Kolarsky" <rljc@worldnet.att.net>
To: <hwang@phy03.phy.ntnu.edu.tw>
Dear Dr. Hwang:
Thanks for fixing the link and making the page available again.
I have been looking for a while for this type of an on-line physics textbook. Your page is just great.
Please keep up this good work. I work as a geologist/applied geophysicist at Shell in New Orleans.
Originally, however I was born in Czechoslovakia and came to the U.S as a political refugee in 1987.
I will never forget my high school physics professor (whose picture my wife and I keep on our web page)
I had there as a student. He did quite a bit for me.
Thanks again. SHould you efer come to New Orleans (a convention perhaps) please do not hesitate to let us know.
Sincerely,
Radim Kolarsky

vdusa

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pulley
« Reply #4 on: January 09, 2007, 11:39:03 pm »

let me try

in the 1st case, 2T=mg, T-tension in the rope & m-mass of harry

therefore tension would be 250N which is well below the max tension the rope can sustain.

in the 2nd case,T=mg

i.e., tension is 500N which the rope cannot support.

& therefore it breaks injuring him

is it correct?


Dosie

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Re: Pulley
« Reply #5 on: September 07, 2007, 07:33:31 pm »
ummm

Dosie

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Re: Pulley
« Reply #6 on: September 09, 2007, 03:33:37 pm »
http://i dont get it

Fu-Kwun Hwang

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Re: Pulley
« Reply #7 on: September 09, 2007, 04:58:01 pm »
For the left case : two ropes are supporting the person's weight.
However, only one rope is supporting the person's weight, which is not enough.

Quest4PMD

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Re: Pulley
« Reply #8 on: December 02, 2008, 10:59:02 pm »
Do you have another simulation where the sizes of pulley wheel can be changed?

Gyro

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Re: Pulley
« Reply #9 on: December 20, 2008, 04:19:21 am »
A very good simulation that can be used to teach this topic in a visual manner.  Thank you very much for taking the time to create and share these Java simulations!  Kudos on an excellent web site.

borg911

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Re: Pulley
« Reply #10 on: May 18, 2010, 08:26:51 am »
I'm doing some pulley problems with some 7th graders but mine are a little different. They are all rescue systems for rope rescue. The one I'm trying to do is a 9:1 lift system with 4 pulleys, 2 of which are tied to an anchor, & 2 of which are attached to ascenders. One end is connected to the load (typically the rescuee) & the other end is attached to the people doing the lifting (rescuers). If you think of 2 "z"s connected from the tail of one to the head of another, that's what the system is like. I have it set up in the classroom to do but I wanted to make sure I have the force diagram right.
O = Pulley  r = ascender (allows rope to move in 1 direction only)
| = Shows connection between pulley & ascender.  Normally Pulley is attached to ascender with a locking cabiner

  Load -----r-------------------O(Anchor)
   | ----
   | ----
   | ----
   O-r----------------O(Anchor)
   | ----
   | ----
   |----
   O--------------- Rescuers Pull Here


Fu-Kwun Hwang

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Re: Pulley
« Reply #11 on: May 18, 2010, 11:29:10 am »
It will be easier to understand the case
  if you can draw it ,and upload the image file?
 

mendenn

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Re: Pulley
« Reply #12 on: April 25, 2012, 03:59:30 am »
I downloaded WheelAxle.zip. it doesnot work offline.

Fu-Kwun Hwang

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Re: Pulley
« Reply #13 on: April 25, 2012, 12:05:38 pm »
Unzip the file and go to WheelAxel sub-directory, open pulley.html with your browser.
wheelAxle_pt_57936.html did not work. You need to move it to WheelAxel sub-directory

4uxxxxx

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Re: Pulley
« Reply #14 on: June 17, 2013, 01:52:21 pm »
Thank you so much sir :)