Physics

Hello everybody, I found this forum while trying to find an answer for a question(and am quite exited about the plethora of knowledge you've got here). I hope I'm posting in the right forum(since launching space shuttles is still largely dependant on newton's physics) I've been watching the launch videos of a few space shuttles on youtube and noticed that all of them go up vertically in the beginning, but after reaching a certain point they will fly at about 45 degrees from what I saw. First I thought it's because shuttles don't leave earth orbit so they need to kick into orbit and start going horizontal a bit early, but then I saw that Apollo 11 did the same …

Would light speed up or slow down in the presence of gravity?

When considering an electromagnetic plane wave, the electric and magnetic fields are maximum and minimum at the same time. What happens to the energy (Poynting vector S = E x B) as a function of time? It would seem that S is maximum when E and B are maximum and would be 0 when E and B are 0. The instantaneous energy at any given time seems to contradict energy conservation. Thanks for your input.

Hi Im a student who is doing a project which in part requires the use of the triboelectric effect to charge up dust and then look at the effects of this dust when it comes into contact with a low frequency antenna. I didnt study this at school so all I have to go by is the wikipedia page on the subject, my tutor want to measure the polarity and the amount of charge on a rubber balloon when it is rubbed against various materials (eg wool and polyester.) Does anyone here know how to measure the polarity and/or strength of charge on a triboelectrically charged balloon? Also Iv assumed that simply putting the dust or sand into contact with the charged balloon wil…

I wasn't sure where this question should go, so I'm posting it here. What's a good example of a particle that fissions to produce two particles with opposite spins?

A spherical shell has inner radius R-in and outer radius R-out. The shell contains total charge Q, uniformly distributed. The interior of the shell is empty of charge and matter. Find the magnitude of the electric field within the shell, R-in <= r <= R-out. Basically find the E-f within the sphere. I don't really think I understand it. The charge lies all on the exterior, so the interior surface must have -Q. I have tried several different answers, but they say that it depends on R-in and, I assume R-out. I know its a Gauss problem and E = Q/A*e-0, but I am having trouble finding the Q. Do I find the volume density of the big sphere and multiply it…

Hi, I would like to know why compound microscopes magnify the intermediate image to create the virtual image, instead of directly magnifying the target object. Is it something to do with the image being inverted, flipped, inside out or just distorted? I've attached a very basic essay which anyone interested in replying can review, the passage in question reads as "The second lens is basically just a magnifier, however instead of directly magnifying the original object, the lens magnifies the intermediate image and creates what can be described as an enlarged, inverted ‘imaginary image’ which is then projected into the eye which in turn, forms a real image." DI-Es…

What's the scientific word for this? Like... not comparable in a sense.

Is there any specific object/equipment that you can use to measure the dielectric breakdown of air? Or if there's no such equipment, is there any way to fix together some lab apparatus to construct something which can do so?

Well, I dont know how many of you have seen this site: http://www.u-starvin.com/micromaniac/ They microwave alot of stuff - I understand it all, except the christmas lights. how do they light up?

I understand that e.g. pollen grains reflect the movement of the molecules in the e.g. water around them Perhaps the induced movement of the pollen indicates that they have absorbed some energy and this generates some heat through friction, returning it to the system as the molecules lose heat to the pollen This, like the rotation of planets, looks like 'perpetual motion', so may I ask what is really going on?

First, whats it called when your brakes fail from too much heat? Second, how does this happen? Why does excessive heat cause the brakes to fail to put enough pressure on the disks? thanks

Bullet proof glases contain polycarbonate layer sandwithed between two glass layers. How polycarbonate layers prevent bullets? Does it totally prevent piercing of glass? Is it directional i.e is from one side only?

In one book I read about boiling water in a paper cup. Actually I tried heating a water in a paper cup till it becomes hot. Paper did not burn. I am interested to know the principle behind it. Similarly one more article in the book says If you roll a pencil with paper and heat it in a flame paper does not burn ( This I have not tried)

Electromagnetic radiation that is ionizing and is able to bring about changes in atoms is called ionizing radiation. Correct? So my question then is, can any portion of the Electromagnetic Spectrum be ionizing? Can you for instance, have ionizing blue light? Or do certain portions of the electromagnetic Spectrum such as visible light only come in non-ionizing packages?

What is involved in making a week source of microwaves, something small that isn't attached to the steel box you'd normally expect a microwave to come with and with less power that runs of batteries but that produces micowave frequency electromagnetic waves?

If an ice cube is dropped in a glass of water what happens to the level of water after melting of ice? increase, decrease or remain same?

When there is an electrical current running through copper what temperature or temperatures does the copper wire strand reach?

I know that when you rub a balloon against your hair or a piece of wool that electrons are stripped from them and go across to the balloon, giving the balloon a negative charge. And you can rub a glass rod with a piece of silk and the rod loses electrons, making it positive. But what I don't understand is why the electrons move across to the different materials. What property of the material determines whether it will lose or gain electrons? Any help would be great.

I don't get how an electric current can go through a conductor faster than the individual electrons flowing through. How can the electrons make a current go across a conductor at the speed of light when the electrons themselves aren't moving across the conductor at that speed?

Kind of a very basic question, but I am not basically a physicist. A bucket with two holes on its sides is filled with water. If the bucket is allowed to free fall from a tower, will the water fall through the holes OR the water will not fall OR the water will spill from the top of the bucket ????

Hi, I am after some advice from you guys, it would be much appreciated.... I am looking for your recommendation on the best material that when placed out in the sun all day would have heated up very well and then continue to hold that heat with not much loss (or very slowly) all through the night, so that are small area could be heated Any ideas? I have been looking at cast iron which seems good but to be honest it's one of the first I came across! So I thought i'd approach you guys for more expert advice, You suggestions would be much appreciated and thanks in advance. oh, a lightweight material would also be an advantage, thanks

Why warm water freezing faster than cold water? Can somebody explain this?

Does anyone know exactly how an inductance transmitter works? Any input would help .. Thanks

Hi all. If a lenght of empty (with atmospheric air) aquarium hose is plugged with beads of silicone sealant at the ends; and placed inside a plain household water pipe... When the water pipe is placed in operation, at say 3 Atm water pressure, the hose inside will contract/deform due to the pressure. Would the plugs at the ends tend to burst outwards or inwards or will not be affected at all ? Just want to confirm am not missing something here... Miguel