Classical Physics

I was talking with some people in physics about this: Where is the center of mass of Gabriel's Horn? What would the moment of intertia be when rotating around the x-axis or x=1?

Theoretically, if the multipactor effect causes electrons to go into a kind of statis, where they can't move, wouldn't that mean, due to the whole thermoelectric effect, that it would keep thermal energy from transfering from one particle to another?

I posted this a while ago in the pseudoscience forum, but didn't really get the response I hoped for, so I'm posting it here. I know gravity control techniques are generally viewed with skepticism, and quite probably pseudoscience, but I can't find anything refuting this article (or otherwise), and don't know enough myself to judge whether it makes sense or not. So what I'd like to know is whether or not there is anything to what's described in the article. Does General Relativity predict such an effect? Theoretically, going by the information contained in the article, should it work or not? (And why?) Also: I have absolutely no idea how this could possibly h…

If I built a large hollow sphere from an extremely dense material (dense enough so that the shell has noticeable gravitational effects) what would the gravity inside it be like? Would objects fall towards the inner surface, or fall towards the empty center? Or would they fall towards the inner surface, while their acceleration decreased the closer they got to it? I ask because visualizing this using the famous rubber sheet analogy (representing the sphere as a ring, since I'm removing a dimension in doing this...), it seems like the gravitational attraction should be towards the shell, regardless of whether you're inside or outside it - this makes sense intuitively, t…

I tried looking at the formulas at a site, and I had no real idea of what I was looking at. All I'm really looking for are some generalities anyway. (Although if someone wants to take a swing at even pointing me in the right direction of the right formulas that would be a start.) Basically, a 0.4 pound object traveling at 73.3 feet per second would impact on a target with what kind of force? The other item I'm trying to get a grasp on, is a 80 pound object that is thrown (so I really don't know how fast it would be going) would impact on a target with what kind of force? Any help would be appreciated.

Hi. This is not my field of expertise at all, am begging your assistance. In a gasoline automobile engine, given the intake manifold absolute pressure, the displacement, the revolutions per unit of time, the air temperature and a throttle position reading ; is it possible to precisely calculate the air mass flow ? Or more information would be needed ? Miguel

I was wondering something today. Given a simple liquid barometer, the idea is to have two connected surfaces of a fluid, one exposed to vacuum, the other to air. The weight of the air column above the air-exposed surface forces the other upwards until the weight of the difference in height is equal to the air pressure. Right? Right. Now what I'm wondering is, won't there always be vapor in the vacuum chamber as some of the liquid boils when exposed to vacuum? If so, how negligible is the pressure exerted by said vapor, and how does it relate to the exterior air pressure? Does it in any way depend on the liquid used?

Is there any way on knowing for certain the speed in which gravity acts, compared to the speed of light? If gravity works at light speed, - considering no particle can move faster than light speed - that could be evidence suggesting there is a force carrier particle, the graviton, although it wouldn't be conclusive proof. If gravity acts truly "instantly" then it would most likely rule out the existance of any force carrier particle, for the same reason as stated above. I believe that gravity is nothing more than an inherent mathmatical value acting on the physical laws of the universe; that gravity is just a manifestation of a mathmatical attribute. Has t…

</David Essex voice> does anyone know how to calculate or work out the similarities between a bullet projectile using Foot/Pounds and a bow and arrow with a draw weight of 55 pounds? my bow`s a 60 inch Ben Pearson 3350, with a drawing weight of 35-55 pounds, how does it compare to the legal 12 foot pounds (or less) for an air gun?

A prism of refractive index 1.52 is completely immersed in water of refractive index 1.33. A point source of light in the prism lies 60.0 cm below the at interface between the prism and the water. What is the diameter in centimetres of the circle at the interface through which light emerges from the prism? (a) 52 (b) 105 © 108 (d) 137 (e) 217 answer is (e) but I tried everything.. with no luck I calculated that the angle of incidence the light must approach the water and air must be 48.75.. past that point its all futile, the prism fubars everything up sry for posting this, but it isn't a homework question, rather a review question that I just can't …

If we assume that gravity curves spacetime doesn't that mean that we accept there is an ether otherwise there is nothing to curve.

A plane is standing on a runway that can move (some sort of conveyer belt). The plane moves in one direction, while the conveyer moves in the opposite direction. This conveyer has a control system that tracks the plane speed and tunes the speed of the conveyer to be exactly the same (but in opposite direction). The question is: Will the plane take off or not?

Hi, I've just found the hall coefficient for some Bismuth film samples experimentally, at room temp, and am struggling to find any book values for it, the density of charge carriers or the hall mobility of Bismuth. If any one knows any sources for any of these values they'd be greatly appreciated... Cheers Klay

I've been given a challenge by my grade 11 physics teacher and I can't make heads of tail of it, I’ve got the formulas but the numbers don't make sense. If you went up 109 km (above sea level) and dropped a rock, what speed would it be traveling at and how long would it take to reach 34 km (above sea level). Air resistance can be ignored. Gravitational constant =9.79 m/second*second This is the only formulas he gave me. Where do I even start??? Distance: Distance to be traveled = 109km - 34km Distance to be traveled = 75km I then started making a chart going by 0.5 second increments Example: {Time} (Acceleration…

Hi there everyone! I have a new question. In physics yesterday we learned about how two sound waven in anti-phase and cancel each other out causing there to be no sound as a result. To my question can this occur with light? If for example you could have a light source emitting [acr=Electromagnetic]EM[/acr] light waves then could you in theory find a point where these waves are deconstructivley interfered with resulting in no light? Cheers, Ryan Jones

this site puts the airspeed of an unladen european swallow at 10 m/s

I just made a 70Hz sine wave on the computer, it was pretty kick ass. Everything in my room shook on a standard 120W subwoofer Anyone else want to give it a shot? http://ancient.ssforum.net/70HzOwnage.wav Note: Don't bother if you don't have a subwoofer

here`s a problem I can`t quite figure about Bullets/ammo. they fall into 2 catagories, center and rim fire. both of which need a "Hammer" to strike the primer to start the reaction. now the power a bullet comes out at is incredible! but Newton states that for every action, there is an equal and opposite reaction. so how come, the primer case (being only thin metal) doesn`t rupture and blow off the firing pin?

Here are two questions I am concerning. 1.If we use a solid iron core instead of a laminated one, the Voltage induced will decrease. My teacher said it is, simply by saying more energy loss as heat. P=V^2 / R Power distributed to the secondary coil increases. So V increases,keeping R is constant. But I don't think so. [i think the current can increase instead] 2.This question is relevant to my thought. How is the current in the secondary coil determined? by V=IR? I think it is by P=IV. By then, how could any appliance in the secondary coil affect the current? Consider a step-up transformer. If the V in 2nd coil is very large, V^2/R will violate the law of co…

Hey guys, I was doing gravitation today in physics and we were looking at escape velocities. The velocity is given by: [MATH]v = \sqrt\frac{2Gm}{x}[/MATH] Now this equation only has the value of one of the masses in, so the velocity is only dependant upon one mass. My question is why is this independant of the mass of the object trying to escape? If you were trying to jump off the Earth, you would attract the Earth and the Earth would attract you. Although if you had the mass of the moon your attractive force would be higher, so why does this not mean the velocity would need to be greater for the bodies to seperate compared to you having your mass or the m…

This is just a hypothetical question that I've been wondering about. So I cant remember all of the details, but the earth has a magnetic charge (I cant remember +, -), and then the earths core leeks out and creates the magnetic shield around the earth (Dont know the charge of that either). With a big enough magnet, wouldnt it hypothically be possible to make a craft that balances between the two fields. Such as if the earth holds a posotive charge, and the magnetic field holds a negative charge: The bottom of this craft puts out a very strong (magnet the size of New York) posotive charge, and the top of the craft puts out a negative charge. Since like charges pus…

I've been thinking a lot recently about the creation of energy through gravitational collapse. Is it possible for energy to be created if momentum increases in a non-isolated system where the conservation law (1st law of thermal dynamics) is not applicable. A simple scenario would be someone rolling down a hill...no energy is actually being used (so is conserved) but distance is covered (due to gravity taking hold). If the system doesn't follow the first law (non-isolated) is it possible for energy to be created ? I've vaguely covered this idea when considering dark energy in another thread, but I was wondering if there was anything substantial that could back t…

I've been arguing with some people about a situation in which two completely rigid bodies surrounded in a vacuum collide... they keep saying they will bounce off each other but that doesn't seem right. It's written up here http://midnightwiki.com/index.php?title=Inelastic_Collision. What do you guys think? Also, would there have to be some sort of new energy released if they were to collide?

first,i am not a physics study, though i did have a class in high school 5 years ago. with that said, i am wondering why it is a common belief to think of a solid nickel-iron core at the center of the earth. gravity is the attraction of matter to matter. so the all the matter of the earth is pulling us down. well, if i were at a point where there is matter pulling equally(or close to it) in all directions there would be effectively no gravity. this point/area would be near the center on the earth. Therefore there would be no pressure there and no reason for a solid mass in the center.

Ive been very interested in physics latley and i was wondering if anyone knew of any particular books on physic that would be good for me to read your help will be greatly appreciated.