Classical Physics

Hi all. A litre of water at 25℃ needs a certain amount of calories to become steam at 100℃ ∆t=75℃ (75Kcal + 540Kcal =615Kcal) if I remember the figures. That is a 1 ATM. Under partial vacuum, such energy requierement can be less. Let's say it boils at 45℃ under such partial vacuum ; ∆t=20℃ thus would need 20 Kcal + 540Kcal = 560Kcal ---> Are the calories needed at 1 ATM and under partial vacuum constants ? The difference in energy needed to achieve the same are different under the different pressures. Some extra energy has to be used to run a vacuum pump. ---> Is the sum of energy to boil at 1ATM equal to boil under partial vacuum + the energy…

Please see the attached explanation of the Mechanics of Gravity. mechanics of gravity10.28.09.pdf

I have read in several articles that "As a substance is heated, the atoms and molecules that make up the substance vibrate faster." Now, Newtons Law of Inertia states that "A body persists its state of rest or of uniform motion unless acted upon by an external unbalanced force." So what is causing the vibration?

Is there such a thing as an isothermic irreversible expansion of a gas against a constant external pressure? Could some one give me a physical example of one?

This one has bugged me for a while. Does magnetism actually involve 'lines of force,' along which so many beginner experiment descriptions have iron filings aligning? Or is it an actual non-discrete field effect like gravity?

For a high school physics competition I need to build a cart that is powered by a 1kg hook weight that will be dropped from 1m above the ground. This is a distance competition. The course will be flat. There is no limit to the size of the cart but it needs to fit in a 6ft wide course. The organizers will give me the weight and I can attatch it anyway I want as long as it fits the above decription. Also, no vaults or ramps are allowed. Any help you can give me will be greatly appreciated.

My question is fairly simple, yet the combined powers of Bing and Google cannot seem to answer it. How much energy does it take to compress a solid?

Hello, I'm looking for a graph or values of the refraction index of water in the mid-IR region. Can anyone help ? McCrunchy

Although I am no expert in plasma physics, I am quite fascinated by the topic and I do have some questions. The first question that I have is: Is the temperature of the electrons or the ions in a small volume of an anisotropic plasma better expressed as a rank 2 tensor or a rank 1 tensor (vector) as opposed to a scalar? I know that the magnitude of the temperature should always be a scalar. However, I think that the temperature of the electrons is related to the velocity as in K[math]^{ }_{b}[/math]T[math]^{ }_{e}[/math]=M[math]^{ }_{e}[/math]V[math]^{2}_{e}[/math] Where K[math]_{b}[/math] represents Boltzmann's Constant Because the velocity of the parti…

Hi, I'm having a really hard time understanding this question. I am not looking for someone to show how it's done, but just help with me drawing free body diagram because it is really driving me crazy (I've spent at least 2 hours just to do that and go nowhere). Thank you! Problem: An elevator cable winds on a drum of radius 90.0 cm that is connected to a motor. (a) If the elevator is moving down at 0.50 m/s, what is the angular speed of the drum? (b) If the elevator moves down 6.0 m, how many revolutions has the drum made? My issue is that I don't understand what this "drum" is for elevator. I've never heard of it before.

Ok, simple question: Say I'm standing on the ground on Earth. I'm not moving, so I'm pushing down on the ground with a force of my mass * 9.81 m/s2. Now, I jump straight up, and in doing so, I push on the ground with twice that force. Thus, I should accelerate upwards are 9.81 m/s2. Would I say I'm "pulling 1 G" (based on my acceleration) or "pulling 2 Gs" (based on the force on the ground, including the portion supporting my body weight)?

I was browsing wikipidia today on the subject of Magnetic and Internal confinement reaction in nuclear plants because I feel nuclear energy is the way forward when it comes to alternative energy sources and it interests me. However I came accross the following: http://en.wikipedia.org/wiki/File:Inertial_confinement_fusion.svg "Schematic of the stages of inertial confinement fusion using lasers. The blue arrows represent radiation; orange is blowoff; purple is inwardly transported thermal energy. 2. Fuel is compressed by the rocket-like blowoff of the hot surface material. 3. During the final part of the capsule implosion, the fuel core reaches 20 times the d…

Hey everyone. I have an engineering background and I also supervise a science club at a local school. I'm trying to think of ways to relate my applied science knowledge to some more fundamental science in order to better represent the mathematicians and fundamentalists. I was thinking of explaining how a lot of engineering properties come from science and math. For example, in grad school I remember the prof deriving the specific heat of a gas from the M-B distribution. I'm somewhat ignorant regarding this since my field was in mechanics and we only ever really had to know what the M-B distribution was. Can anyone recommend a good reference for this? I managed to find…

The conservation of momentum states that when two objects collide the resulting vector is the sum of the other two vectors. Say you have Object A that is 5 kilos and Object B that is 5 kilos. They are moving in a one dimensional path, opposite each other at 5 and -5 m/s, respectively. They then collide with one another in a elastic collision (sticking together the conservation of momentum says that they will stop moving. What happens if I have an electron for object A, with a mass e, and a positron for Object B, with a mass e. They are also moving in a one dimensional path, opposite each other with velocity v and -v, respectively. They then collide with one anothe…

Have you ever heard of a perpetual motion generator? It is essentially an electric generator that is turned by the force of magnets. I'm pretty sure that it is a working design, because a guy that worked on it has refitted his car with it, and it works pretty well. I think it's pretty neat. So many scientists are working to find cheaper energy solutions, like hydrogen cells and air power, and something this simple but brilliant is staring them in the face. Invest in some nice high grade magnets, like grade 50 neodymium magnets, and you have an almost unlimited supply of energy!

Hello all non empty heads. As a layman I was wondering. If light is both a wave and a partical. Does it also exert a gravitational pull however small. and if so might this go some way to explaining why the universe holds together? Dumb question may be. but hey. Dumb guy.

In thermodynamics, is it possible to fin a quantitative and correlative relationship between amount of heat on a disapative structure, to shape of the geometric figures formed?

Sorry about the title, but that's the example I'm going to use in this question. I just have a misunderstanding about something to help clear some things up for myself about a theory of mine I'm working on. Imagine a Ziploc sandwich bag or something similar which can be sealed to be air tight. All of the air is pressed out of it and it's completely flat. Now imagine trying to pull apart the two flat sides of the main plastic body. You won't be able to because no air or anything else is able to seep in to it in order for the bag to expand or blow up. Also, because of the pressure of the earths atmosphere I guess. Here's my question: If this were attempted…

Hi, Does anyone have any past research work on 'physical properties of currency notes'/ 'variation of their properties with usage'? or of a relevant topic such as any research work on physical properties of paper? I tried browsing around, but didn't find much on this topic. Where would be the best place to look on this case? Thanks

How do we know that 3 base colors are needed to compose any color and not 4 for example ? Is there a physical proof from medical analysis of eye's cell ? --- btw : if it were a palette we would need 2 to localize the color : distance right and up from a corner for example.

A stationary Muon decays far quicker than a Muon moving near the speed of light. According to the special theory of relativity time dilates, so the decay rate for the moving muon slows down. Because time slows down. But according to SR something different happens to particles moving close to the speed of light, they gain mass. So could the extra mass account for the slower decay rate of the moving muon?

I do hope I've posted this in the right forum. Apologies if it isn't. I need to know how much weight a latex balloon filled with helium can lift and still happily sail away into the sky. I know there's no real 'standard' size for a balloon, but if you can imagine your typical birthday party balloon, that might help. What I *don't* mean are the foil balloons. I realise that to answer this question, you would need to know how much helium is inside a balloon. I don't have an answer to this and I'm hoping that you can guess an educated guess to estimate how much would be inside a balloon. So, to clarify, I would like to know as accurately as possible how much weig…

there is no air in space, thus no friction. So if light is thrown off by like a pulsing dying star or a super nova, there should be nothing slowing it down. and what happens when the light hits like(if possible)2x the speed of light. Does it enter a whole diffrent demsion or does it just keep speed ing up? i'd really like to know!~

I just can't seem to get my head around Newton's third law of translation. The one about every force having a equal and opposite reaction force. If you push a door with 10N and the reaction force is 10N in the opposite direction of the initial force surely the forces cancel out and the door doesn't move at all. Isn't this the same as if two equal forces are supplied on either side of a moveable object in opposite directions the object doesn't move. Obviously there is a huge missing link that I'm too stupid to see.

I read in my physics book the following which is confusing me slightly. “Consider a pair of tennis balls, one a regular hollow ball and the other filled with iron pellets. Although they are the same size, the iron filled ball is considerably heavier than the regular ball. If you hold them above your head and drop them simultaneously, you’ll see that they strike the ground at the same time. But if you drop them from a greater height- say from the top of a building you’ll note the heavier ball strikes the ground first. Why?” It then goes onto explain why and I can follow and understand the argument with no problem BUT what is confusing me is that I’ve heard that…