Yep, thats a beautiful example.
Youve got three terms added together: pressure, ½ density * velocity^2, and density *g*height. The first one is Pascals (N/m^2) because its pressure. The second one is Pascals because its density (kg/m^3) times velocity^2 (m^2/s^2), which when you cancel units is also N/m^2. ( N=kg m/s^2) The third one is Pascals because its density (kg/m^3) times g (m/s^2) times h (m), which when you cancel units is also n/m^2. Only when you get all three right to they add as Pascal, Pascal, and Pascal. Nat From: Martin Vlietstra [mailto:[EMAIL PROTECTED] Sent: Friday, 2008 January 18 16:30 To: [EMAIL PROTECTED]; 'U.S. Metric Association' Subject: RE: [USMA:40146] Re: Metric in Physics class In my first year Physics class (1965), they took a totally different approach. I was in South Africa which at that time still used imperial units. We studied Bernoullis equation fairly early on an equation that relates fluid flow, pressure, pipe diameter and fluid head. In our first test a problem was presented to us in a variety of inconsistent units. Unless you got your units right, you got the problem wrong. I never forgot that test. _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Nat Hager III Sent: 18 January 2008 18:44 To: U.S. Metric Association Subject: [USMA:40146] Re: Metric in Physics class All I can say is for Introductory Physics I and II - for bio premeds we never use Imperial and the subject never comes up. Between that and grant-sponsored research, I think the only time I have real exposure to Imperial is at the hardware store Saturday morning. Nat From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mike Millet Sent: Friday, 2008 January 18 12:58 To: U.S. Metric Association Subject: [USMA:40145] Re: Metric in Physics class Well, we had our refresher course today on the metric system and the reaction was mixed. Several people who had previously been opposing it saw how easy it was and now like it, and several people have agreed that even though it's not what they would prefer they'll use it "just for this one class". There were still a few diehards that were complaining about it but that number shrunk drastically from the original. Now if only the problems themselves would get more understandable. I have a feeling that this will be one of my more challenging courses this semester. Mike On Jan 18, 2008 6:33 AM, Nat Hager III < [EMAIL PROTECTED]> wrote: I teach intro college physics, and have for years. The first day in September we cover meter, kilogram, and second, along with uncertainty and significant figures. Imperial units are never mentioned, and never asked about in class. Nat -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ziser, Jesse Sent: Friday, 2008 January 18 1:31 To: U.S. Metric Association Subject: [USMA:40138] Re: Metric in Physics class I don't think you have to be that hard core to be a metric user in physics. Actually, my experience has always been that physics mostly uses metric. I think in all intro-level physics classes I had in college, the metric system was introduced at the beginning and used throughout. I went to school at the University of Texas at Austin... don't know if we're just special or what. Certainly, in my electrical engineering courses there wasn't an inch to be seen. My dad is a community college professor of biology. I didn't know if he had any particular feelings regarding metric units, but when I mentioned to him that I was interested in promoting US metrication, he responded supportively, quickly pointing out that in every bio lab he teaches, he has to waste time explaining metric units to his students. He added that he always makes it very clear to them that "the only reason we have to have this stupid section is because this is the only country in the FREE WORLD" [emphasis his] that refuses to use reasonable units. I think there is a lot of simmering, silent, but strong support out there, especially among educators, scientists, and engineers. It's just that what happened in the 70s kind of wiped out any feeling of enthusiasm among most people that the US could ever change, even if it wanted to. --- Patrick Moore <[EMAIL PROTECTED]> wrote: > I wonder if the professor was consistently hard core and used radians (not > degrees) for plane angles. > > > > From: Mike Millet <[EMAIL PROTECTED]> > Reply-To: <[EMAIL PROTECTED] > > Date: Wed, 16 Jan 2008 23:12:18 -0700 > To: "U.S. Metric Association" <[email protected]> > Subject: [USMA:40109] Metric in Physics class > > > By some random curse this semester the only science class I could take that > fit into my work schedule was Beginning Physics. > > I wouldn't have taken it except for the fact that it fulfills my goal for > the general credit and I figured I may as well give it a try. Having heard > some of the stories on this list about people walking in on engineering or > other classes to find a bizarre mix of US and metric measures, I was kind of > wondering how this professor would address it. > > Luckily for me, he announced the first day of class that in his classroom > all problems and discussion would refer solely to metric units, and that > there would be no inches, feet, miles, etc in any of the problems or during > any of the discussion. > > Several people objected to this and asked him to use "normal" measurements, > but he politely informed them that for the majority of the world the SI > "was" the normal unit of measure. He also mentioned that physics was an > exact science, and said that you couldn't get any more exact than the metric > system allows, certainly not with decimal or fractional inches. > > The first problem he put up on the board was one of those "if train x > travels at a 60 km/h over a distance of x kilometers and train y travels a > speed of 80 km/h over x kilometers, how long would it take before they > meet?" or something to that effect. > > When he asked for questions on the problem, several hands shot up with the > invariable "what's a kilometer?". They then explained that although they had > been taught metric in passing, their teachers never insisted on a great > familiarity with it, and so they had never learned the basics > > As a result of this, we are having a refresher course on metric measure > during tomorrow's class. That way everyone is on the same page from now on. > > It doesn't make the physics any easier to understand, but I credit the > metric system and my early introduction to it with giving me a greater > chance of passing :). Kudos to the professor in sticking to his guns and > finding a way to slowly drag yet another group of students into the modern > scientific world. > > Mike > -- > "The boy is dangerous, they all sense it why can't you?" > > (\__/) > (='.'=)This is Bunny. Copy and paste bunny into your > (")_(")signature to help him gain world domination. > > ____________________________________________________________________________ ________ Looking for last minute shopping deals? Find them fast with Yahoo! Search. http://tools.search.yahoo.com/newsearch/category.php?category=shopping -- "The boy is dangerous, they all sense it why can't you?" (\__/) (='.'=)This is Bunny. Copy and paste bunny into your (")_(")signature to help him gain world domination.
