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21. friction (score: 67)

Author: John Denker <jsd@av8n.com>

Date: Tue, 26 Sep 2017 15:13:52 -0700

On 09/25/2017 12:31 PM, Anthony Lapinski wrote: Kinetic friction does negative work on a sliding book, which makes it stop. And static friction moves us forward when we walk. But there is no slipping

/archives/2017/9_2017/msg00112.html (9,250 bytes)

22. ENERGY WITH Q (score: 64)

Author: Bob Sciamanda <trebor@VELOCITY.NET>

Date: Tue, 30 Oct 2001 09:35:47 -0500

The integral of the net external force over the trajectory of the system CM will ALWAYS equal the system KE change. See previous (1999?) list discussions. Bob Sciamanda Physics, Edinboro Univ of PA (

/archives/2001/10_2001/msg00773.html (11,109 bytes)

23. There's work, and then there's work (score: 59)

Author: "John S. Denker" <jsd@MONMOUTH.COM>

Date: Thu, 23 Jan 2003 08:47:23 -0500

But wait, there's more: (0) the microscopic work/KE theorem of mechanics. Note I didn't say "CM work". Item (0) is what I call "the" work/KE theorem. I believe this is 100% standard terminology. I w

/archives/2003/01_2003/msg00199.html (4,832 bytes)

24. ENERGY WITH Q (score: 58)

Author: John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>

Date: Sat, 1 Dec 2001 11:06:10 -0700

On Sat, 1 Dec 2001, John S. Denker wrote: Eugene Mosca wrote: It seems to me this involves an understanding of only the center-of-mass work-translational kinetic energy relation. Am I missing somethi

/archives/2001/12_2001/msg00013.html (12,545 bytes)

25. ENERGY WITH Q (score: 58)

Author: "John S. Denker" <jsd@MONMOUTH.COM>

Date: Tue, 30 Oct 2001 09:28:59 -0500

At 08:30 AM 10/30/01 -0500, Carl E. Mungan wrote: I'm confident you agree that for an object with or without internal degrees of freedom and having total mass M, the net force (which is of course ext

/archives/2001/10_2001/msg00772.html (8,621 bytes)

26. Work-energy worries (score: 54)

Author: "Carl E. Mungan" <mungan@USNA.EDU>

Date: Fri, 11 Oct 2002 14:48:22 -0400

And there is a *genuine* point of departure. I stand by everything I have written in this thread and am content now to leave it to others to judge the merits of the arguments that have been put forwa

/archives/2002/10_2002/msg00254.html (8,443 bytes)

27. Work-energy worries (score: 54)

Author: "Carl E. Mungan" <mungan@USNA.EDU>

Date: Fri, 11 Oct 2002 15:02:46 -0400

Sorry! A few small details in my last message were not clear. Please discard it and replace it with this version: And there is a *genuine* point of departure. I stand by everything I have written in

/archives/2002/10_2002/msg00256.html (8,569 bytes)

28. ENERGY BEFORE Q (score: 54)

Author: "Carl E. Mungan" <mungan@USNA.EDU>

Date: Fri, 19 Oct 2001 14:24:33 -0400

Model 2a --> a little more realistic world with nonconservative forces, but no dissipation (no entropy production). Example: Charged particle in time-varying magnetic field. 2) If OTOH we are talking

/archives/2001/10_2001/msg00508.html (10,262 bytes)

29. Why work before energy in texts (score: 47)

Author: "Carl E. Mungan" <mungan@USNA.EDU>

Date: Mon, 15 Oct 2001 13:01:43 -0400

Now if I slide the book across the table slowly, there are again two forces acting -- my hand and friction -- and the work done by each force cancels. See the book does not continue to move -- the le

/archives/2001/10_2001/msg00317.html (6,402 bytes)

30. Car acceleration (score: 41)

Author: John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>

Date: Tue, 5 Feb 2002 15:48:40 -0800

On Tue, 5 Feb 2002, John S. Denker wrote: But it would be so much easier to describe the center-of-mass motion of the car in terms of momentum. And there is no need to mention thermodynamics in conne

/archives/2002/02_2002/msg00197.html (5,406 bytes)

31. A "heat" question (score: 40)

Author: "John S. Denker" <jsd@MONMOUTH.COM>

Date: Fri, 29 Nov 2002 05:00:48 -0500

Carl Mungan wrote: Each iteration of the heat, work, and energy discussions slowly evolves my understanding. What a thorny topic. But worthy of consideration, not just stubbornly clinging to current

/archives/2002/11_2002/msg00392.html (10,326 bytes)

32. There's work, and then there's work (score: 39)

Author: John Mallinckrodt <ajm@CSUPOMONA.EDU>

Date: Thu, 23 Jan 2003 08:08:58 -0800

Title: Re: There's work, and then there's work Eric Lane wrote Where can we find definitions of 0) the microscopic mechanical work 1) the mechanical pseudowork, which at least one person calls work,

/archives/2003/01_2003/msg00204.html (6,981 bytes)

33. There's work, and then there's work (score: 39)

Author: John Mallinckrodt <ajm@CSUPOMONA.EDU>

Date: Thu, 23 Jan 2003 08:15:30 -0800

(Oops, somehow that last message got "formatted." Let me try again ...) Eric Lane wrote Where can we find definitions of 0) the microscopic mechanical work 1) the mechanical pseudowork, which at leas

/archives/2003/01_2003/msg00205.html (6,209 bytes)

34. Car acceleration (score: 36)

Author: "John S. Denker" <jsd@MONMOUTH.COM>

Date: Tue, 5 Feb 2002 01:23:17 -0500

1) Scott Goelzer wrote that according to some students, it is the _engine_ that makes the car go. The students may be 100% correct, depending on details of what the question was. 2) Many others have

/archives/2002/02_2002/msg00164.html (10,048 bytes)

35. BEFORE "Negotiating" a curve. (score: 36)

Author: John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>

Date: Tue, 9 Nov 1999 09:07:28 -0800

On Tue, 9 Nov 1999, Ludwik Kowalski wrote: Suppose a cylindrical wheel is set to roll on a flat horizontal surface in a good vacuum. Its mass and radius are known and the kinetic energy, is initially

/archives/1999/11_1999/msg00389.html (7,736 bytes)

36. first law of thermo (score: 34)

Author: John Mallinckrodt <ajm@CSUPOMONA.EDU>

Date: Tue, 17 Sep 2002 21:43:53 -0700

John Denker wrote: "Carl E. Mungan" wrote: F = m dv/dt => F dot dr = m v dot dv Integrate both sides to get desired result W = delta(K). Add subscript "com" to W and subscript "TR" to K if you prefer

/archives/2002/09_2002/msg00422.html (9,066 bytes)

37. There's work, and then there's work (score: 33)

Author: Jim Green <JMGreen@SISNA.COM>

Date: Thu, 23 Jan 2003 12:24:30 -0700

PS But if one really wants to muddle the student's mind, then talk about pseudowork -- a totally unnecessary and even counterproductive concept I would call item (1) the pseudowork/pseudoKE theorem.

/archives/2003/01_2003/msg00218.html (4,252 bytes)

38. Car acceleration (score: 33)

Author: John Mallinckrodt <ajmallinckro@CSUPOMONA.EDU>

Date: Tue, 5 Feb 2002 18:07:23 -0800

On Tue, 5 Feb 2002, Robert Carlson wrote: ajmallinckro@CSUPOMONA.EDU writes: 1. Using pseudowork = change in KE Fd = mv^2/2 => v = sqrt(2Fd/m) If you are saying static friction is doing work, then ho

/archives/2002/02_2002/msg00203.html (4,284 bytes)

39. Car acceleration (score: 33)

Author: Robert Carlson <Raacc@AOL.COM>

Date: Tue, 5 Feb 2002 22:12:54 -0500

But I'm *not* saying that static friction is doing work here. I'm saying it is doing pseudowork. It also does pseudowork (of the negative gender) on a disk rolling down an incline. This is confusing

/archives/2002/02_2002/msg00206.html (4,361 bytes)

40. Car acceleration (score: 33)

Author: Robert Carlson <Raacc@AOL.COM>

Date: Tue, 5 Feb 2002 22:12:57 -0500

But I'm *not* saying that static friction is doing work here. I'm saying it is doing pseudowork. It also does pseudowork (of the negative gender) on a disk rolling down an incline. This is confusing

/archives/2002/02_2002/msg00207.html (4,331 bytes)

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