tag:blogger.com,1999:blog-5088860151651047897.post6532251787013769104..comments2024-03-25T10:56:59.380-04:00Comments on Jacobs Physics: Precise language: lose the "potential" in "potential energy"?Greg Jacobshttp://www.blogger.com/profile/03854009948036330746noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-5088860151651047897.post-90995641952365380932013-05-05T10:31:37.239-04:002013-05-05T10:31:37.239-04:00I like your formulation... At the general level, a...I like your formulation... At the general level, and when I teach AP Physics 1 eventually, I'll go with the verbal approach: "Spring energy is converted to kinetic energy and work done by friction." Then they can use that verbal description of energy conversion to write an equation to solve.Greg Jacobshttps://www.blogger.com/profile/03854009948036330746noreply@blogger.comtag:blogger.com,1999:blog-5088860151651047897.post-38142940792342748602013-05-03T12:28:13.943-04:002013-05-03T12:28:13.943-04:00If you eliminate the idea of "potential"...If you eliminate the idea of "potential" energy, do you have a clever way of writing a large conservation of energy formula? Maybe just E0 + Wnc = Ef? That's definitely shorter than U0 + K0 + Wnc = Uf + Kf, but I'm not sure it'd be easier for students to use. Maybe I'm wrong though, and with practice they'd figure it out.Mike Vnoreply@blogger.comtag:blogger.com,1999:blog-5088860151651047897.post-56938668192429589232013-04-22T18:41:21.764-04:002013-04-22T18:41:21.764-04:00To annotate Greg's final scenario:
So consider...To annotate Greg's final scenario:<br />So consider a ball dropped from 2 m high onto a vertical spring. What's the energy conversion? I've trained my students to write "gravitational potential energy is converted to spring potential energy." But having read through stacks of papers, I see that Jeff is right. How often have I read "potential energy is converted to potential energy?" Or even with a correct statement of energy conversion, how many times have I seen the resulting equation written as "mgh = mgh"?<br /><br />I would say, "The energy is initially stored in the ball's height (elevated position) in earth's gravitational field. The energy then progresses to being stored more and more in the motion of the ball as it falls down from higher heights gaining speed. The energy is then stored more and more in the compressed spring, BUT that compression AND MOTION are mpt storing MORE of the energy until the net force on the ball becomes zero (spring force balances gravitational field force). Eventually all of the energy changed from being at a higher height is now in the compressed spring.<br /><br />I'd DO this conversation around a series of pie charts that all have the same area and three different pie pieces of varying sizes. Create a pie chart at H, 3/4 H, 1/2 H, 1/4 H, and 0 where H is the height of the unstretched spring with the object attached and not moving relative to the lowest position where the spring is maximally stretched and the object is not moving. IF the students know the relationships for the various forms of energy storage (not type of energy), then they can use the pie charts to build quantitative bar charts and/or a single graph of Eg, Ek, and Eel vs h from 0 to H. <br /><br />Understanding that graph IS a high level exercise. It can bring into sharp focus that the position where the FORCES balance is NOT the position where the energy stored in g-field equals energy stored in spring. But, instead, the position where the forces balance is the position where the Ek is a maximum.<br /><br />Pedantic to a fault? Yes, but this is talk among teacher not with students.Gonzohttps://www.blogger.com/profile/13907156621630518166noreply@blogger.comtag:blogger.com,1999:blog-5088860151651047897.post-64144680504068857172013-04-22T09:57:45.941-04:002013-04-22T09:57:45.941-04:00Great comments. In order:
Matt: I see your point...Great comments. In order:<br /><br />Matt: I see your point about understanding other scientists -- after all Feynman hat that very issue with the mathematical symbology he invented. But scientists understand "spring energy" just fine. And your students will figure out the textbook just fine. (I dispute that more than a select few first-year physics students can get much out of a textbook as opposed to in-class work, anyway. Those select few won't have an issue.<br /><br />Drew: Jeff, who initiated the conversation with me, is an AP exam leader. I'm going to remove the word "potential energy" from all my courses. I'm not *advocating* anything; my approach is just that, my approach. I'm offering up a suggestion, but you will not find me criticizing those who choose a different route.<br /><br />David: Wow, I hadn't even considered the "potential" issue. Of course we've all had difficulty with the terminology difference between "electric potential" and "electrical potential energy." Well, if it's just "electric potential" and "electric energy," then there's no confusion. Woo-hoo!Greg Jacobshttps://www.blogger.com/profile/03854009948036330746noreply@blogger.comtag:blogger.com,1999:blog-5088860151651047897.post-2741090694173932322013-04-22T09:24:46.674-04:002013-04-22T09:24:46.674-04:00Yet another vote for dropping the word potential i...Yet another vote for dropping the word potential in potential energy. With AP/honors students I still tend to use it as the generic term for all energies that are not kinetic or dissipative but the individual energies get named after their associated force. I started doing that because I wanted to keep the word potential for use in electricity. Davidhttps://www.blogger.com/profile/05637664210265433149noreply@blogger.comtag:blogger.com,1999:blog-5088860151651047897.post-40276960909628542572013-04-21T13:10:01.363-04:002013-04-21T13:10:01.363-04:00While I like the idea of omitting the word "p...While I like the idea of omitting the word "potential" from the different types of potential energies, I too am concerned about students encountering it elsewhere, including on AP exams. Are you suggesting to drop this word only for conceptual physics courses geared toward younger (9th and 10th grade) students, or are you advocating its banishment altogether, at all levels of high school physics?Drew Austenhttps://www.blogger.com/profile/00082973596707598494noreply@blogger.comtag:blogger.com,1999:blog-5088860151651047897.post-70567756787496102512013-04-21T11:09:14.173-04:002013-04-21T11:09:14.173-04:00Interesting idea. I am concerned about my students...Interesting idea. I am concerned about my students being able to independently use the internet and textbooks to augment their learning. Thus, I worry that if I ban the term "potential energy" from my classroom, it will cause confusion when students encounter the term "potential energy" elsewhere, since it is so commonly used. I agree that the term may get in the way of understanding the concept, but banning the term might also get in the way of understanding other scientists.<br /><br />What about "electric potential" (V)? Same problems? If so, any ideas on a better name for it?Matt J.noreply@blogger.com