tvp45

One of the things you learn early on in adult education (androgogy, as opposed to pedagogy) is that people have learning styles. One might be visual, another might be kinesthetic, but you cannot do much to change that in a fully developed adult. You can either teach/facilitate/demonstrate/assist in an appropriate style or you can literally drive the person to either hate the process or else drop out altogether. Most universities are not capable of responding to the needs of their learners on that level. They have schedules and standards to maintain and it is largely "sink or swim". I took a course in solid state physics in which the professor decided we would cover in 8 weeks a book that often requires 32 weeks, so that we could then try out some of his material. The professor stated that he would move very fast and that, if anyone raised his hand, he would be ignored. If anyone called out a question, that person would be dropped from the class. Only the "cream of the cream" learned anything in that class.

What are your integration limits?

But it's physically impossible for ice to be hot - one could never make a decent Daquiri.

I recommend The Business of May Next by William Lee Miller, University of Virginia Press. This is the story only from James Madison's perspective, but Madison was the father of the constitution save for the Bill of Rights.

Your question may be a little biased. To wit, I am vehemently against abortion. And, I am pro-choice. Should I answer? OK, you choose. Rape victims get to choose at any point. The murder (if that is the correct term) of the fetus is on the rapist's head, not the mother's. (m)62

No, I didn't set the term to zero. The OP stated a massless, frictionless plane, not an incline, not a very thin incline, not something within a limit. I'm OK with that, except then he wants to say "well, it's approximately massless." I'm OK with that also, but I'm not going there. I did my time in solving problems without physical meaning. Now I don't have to. And, I am perfectly comfortable with assuming a cow is a sphere, provided halfway through, you don't say "what about the legs". Let the OP provide his answer.

Good point. IMO, if you don't know anything about the subject, start with an expert. For example, I know nothing at all about how to determine whether goats see colors. I would start with a periodical review, looking initially at known sources like Nature or American Scientist, but also checking to see if there is a peer-reviewed journal named something likeAmerican Journal of Mammal Opthalogy. Once I found a couple of sources, I'd start checking to see who cited whom. Then, I'd try to follow the research grants to see who got them and from where. Then, once I had a couple of names that everybody seemed to like, I'd see if they had any books. If I wanted to work online, I'd Google (which I just now did) and come up with something like this http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Retrieve&db=PubMed&list_uids=9685209&dopt=AbstractPlus Since I have some knowledge of NIH, that's a good starting point. Then I'd try to do the same type of process. Kind of a lot of work, but when I got done I'd be reasonably sure I knew what I was talking about. And, by the way, I would likely have looked at Wiki to see if they had any good sources.

Most high school students are still rather concrete thinkers and will probably have an easier time understanding gravity as a force. They have experience with the idea of force (you can even do action at a distance with magnets and most of them won't raise eyebrows) and can apply that concept to gravity. Most will not yet have conceptualized "fields". That is probably better left for university. All too often, high school teachers "show off" their knowledge and lose students who, at this time in their development, would be happy with simpler explanations.

Well... My point is that primary sources are always so much better than tertiary ones. If I wanted to know something about Newton's Laws, for example, I could read Wiki, Hugh Young, Goldstein, Maxwell, or the Principia or perhaps several. If I were in an ordinary high school, perhaps Wiki does the trick; if I were in a senior level course at CalTech, I think I better not drop below Goldstein. I should point out that Wiki has some excellent articles. I checked a couple before I posted. For example, the one on inductance is first rate. The one on postural control is accurate but not balanced (that's not a bad pun). The one on iron furnaces is OK but not comprehensive. So, I think it requires judgement to use these articles. I'll continue to use it, but not as a citation.

So you have have to decide whether the plane is massless or whether the mass is very small compared to the object on the incline. And, no, they are not the same by any means. But, my answer remains the same: I don't do trick questions that lack physical meaning.

My question would be why use it when good primary sources are available? It's like looking at a picture of vanilla ice cream when a cone of real Cherry Garcia is in your hand.

Forces are, after all's said and done, only a description of what actually happens. You can do all of Physics without the concept of force; it's just easier to use that idea at first. My advice - just accept them and use them.

No, I won't work the second half. I'm not satisfied with your response. Physically, you cannot set the mass to zero and have a force act on this plane; you can only do the limit as the thickness becomes very small.

Do you use tobacco in any form? If so, please see a dentist or oral surgeon immediately.

I'll only solve the first part for now. Maybe later, if I'm satisfied by your response, I'll do the second. The plane is not a material object. It is a 2d ideal. Force cannot act on it to produce a change in momentum; on the other hand, it has no mass (and thus no inertia) to resist a force. Thus, we would find ourselves in the strange position of finding dv/dt = 0/0 and, in the real world, that is undefinable. Keep in mind that we are not taking a limit as the mass approaches 0; you specified a massless plane. Thus, the closest answer is that it does not accelerate. The block M simply passes through it since there is nothing to prevent that. It is really quite close to the invisible plane at the goal line in the NFL; no player can ever hit it so it doesn't move.