Physics

My problem on this question is that I dont have a diffraction angle. A grating with 1500 slits per centimeter is illuminated with a light of wavelength 500 nm. What is the highest – order number that can be observed with this grating?

what would happen if you were to poke a black hole with a very long stick? it might sound like a bit of a stupid question, bit i am being serious. Going further, what would happen if you tied a rope around the earth, and then threw the rope into a balck hole, would we get stucked in? I suppose the rope would snap really. OK what if the string couldnt snap. Anyway i think you can see what i am trying to get at.

I'll be taking physics next yer as a junior in my school and I wonder what are some good books for it. I have no knowledge of physics so I prefer basics. Also, how hard are AP Physics? I don't think my school offer it as "class" but if it's not TOO hard, I think it would be nice to have AP credit on it before going to college. Thank you.

what is total internal reflection? and what does it occurs?

does it exist? if so where?

why are comets only visible from the Earth every few years?

I asked this question to somebody once, and their answer was that they dont, all we can say is that the have in the past. does this mean that theoretically we could say that the whole of existance could just disintegrate at any given moment?

Is true scilence possible? I don't think so as I think that it would mean nothing so moving there'd be no entropy which is practically impossible.

I just love these "will you make me an idea for my science project" threads which I don't think I've ever really replied to. So thought I'd make my own. For those of you who don't know I'm a second year undergrad doing a MPhys, specilising in Quantum Science and Lasers. As part of my stage 2 labs I've got to do an "extended" experiment which should last for 5 weeks of 6hour labs/week. My preference is something quantummy, thinking of attempting to do something with entanglement maybe using an interferometer. I was just wondering whether anyone had any interesting experiment ideas, for obviouse reasons I'd rather not have a great deal of detail given, takes t…

hi every1~ I had the following question on one of my physics quiz, and I need some explanation on how'd you answer it. "A bat detects an object 6 seconds after it emits a high frequency sound of 50,000Hz into aid at STP. How far away is the object from the bat?" That's how I solved the problem: [math] d=t*v=6*331=1986m=d [/math] But my teacher said that I was supposed to use 3 sec. instead of 6. As far as I am concerned, it can be because of taking three sec. to go forward, and the other three to move back. I am not sure what it really means, but just a thought.

I confronted this force problem in the Physics Nelson's Textbook, and my teacher gave us a lot of other questions except this one. I told her, I wanted to do it to challenge myself. But oddly enough, I'm struggling with it. Here's the question: A traffic light hangs in the centre of the road from cables as shown in the figure. If the mass of the traffic light is 65 kg, what force must the cables exert on the light to prevent it from falling? (Hint: Since the angles that cables make with the hortionzal are the same (12 degrees), they both exert forces of the same magntiude. Any suggestions?

I have already posted this in other threads in the biology section of these forums but didn't get many responses. This is why I'm posting it here as I assume people reading it may know a lot more about how these processes could work[and won't be scared off by the word Quantum] [To be honest I'm no Quantum physics expert by any stretch of the imagination, which is why I would be very grateful to know peolpe's opinion on this]. Basically I'm proposing that evolution as we know it is not caused by so called random occurences, but is caused directly by organisms gaining information about their enviroment and adapting because of it. For example from the website: http://w…

i have this question that i have no clue about. y is it that when you wake up in the morning andhow into the shower. the water being hot at about 80 degrees, it feels colder then when u got in. is it due to your body being wet and the lack of heat in the air? thanks a lot if anyone can give me some info on this.

At what point does the effect of earths gravity become zero, and why is it such? Surely at all points in space you should be able to feel some effect (albeit negligable) of gravity. If the effect of gravity does actually become zero, then is there a formula linking the distance you feel zero gravity at, to the mass of a body? I think I might have studied such a formula at school, but i cant remember it. Why isnt the moon on a collision course with earth?

Specific latent heant of V is much greater than fusion, could "energy is absorbed for overcoming the atmospheric pressure" be one possible answer?

If a black hole is a point in space from which nothing can return, does this mean that space itself is lost, and a black hole is actually a genuine point of nothingness, not even vacuum. I know that black holes originate from collapsed stars, and are a very high concentration of mass, but has this collapsed mass has actually fallen through the fabric of space-time. I have heard the question asked, “ since the big bang, what is the universe expanding into?” to which I heard somebody suggest the answer “nothing, absolute nothingness, not even vacuum.” Could black holes therefore be a link to whatever it is that is outside of our universe. Even if that happens to be pure not…

As all atoms are probably 95% vacuum, that makes us probably 95% vacuum, so why isnt dark energy accelerating our expansion in the same way it is supposedly accelerating the expansion of the universe. Is it only an effect of cumulative vacuum, or are we too expanding at the same rate, but cant notice it as everything is expanding at the same rate. If everything was expanding at the same rate, then we wouldnt be able to notice the expansion of the universe. I am confused.

We were discussing this with my Uncle today. Why was Florida chosen to house Nasa. Is there any scientific reason that it should be in Florida? He thinks that Florida had some political influence (senators, money, etc), i.e. politics got it here. Other speculations included being near the ocean, near the equator, and cheaper land.

I know this is probably blatently obvious, but how does propulsion from engines work in space. Does propulsion (such as in the space shuttle) come from the exhaust/stuff coming out the back pushing against the air and ground molecules (or ground when it takes off) and then action/reaction causes it to be pushed forward? If so, in space, there are much fewer particles so how does the propulsion work? As a side note : in space how many particles are there usually (or is it a complete empty vacuum?) I'm confused.

Is there any sort of relationship at all between radiation and radio signals? (If possible, could you provide me with some links related to my question?)

Hi , I am new to this forum and wanted to know the defintion of Universe... What is Universe ? I have been discussing at http://www.scienceagogo.com but it appears that no one has far been able to give me the answer. Regards, Dheeraj

Hello, Im wondering if there is anyway of making a wireless power supply IE transmiting power without cables ? im doing it for a littele experiment. Thanks you guys for all my help on the other question aswell !

If we have a star, let us give an example of Alpha Centuri and a object orbiting it let us label OBJECT X. assume Object x is 1/2 light years away from alpha centuri. if ( and this will not happen, so this question has little purpose) alpha centuri is wiped out of existance, when will OBJECT X stop being influenced by its gravity? suddenly? or after half a year? can no message travel faster than light? and does this link in with the Graviton the assumed particle of gravity

How do Newton's third law, mass, acceleration, impulse, inelastic and elastic collisions, momentum, conservation of momentum, kinetic energy and conservation of energy go together in terms of interaction?

I am a non sceintist but like most ponder. I have a few questions thought this was the place to ask. Here goes. I work with music everyday in which you deal with the bandwidth of human hearing. I am aware of the bandwidth of sight. What about space? It has boundaries ie the speed of light. Whats outside the boundaries of the knowen universe? Could the universe operating in different bandwidths (frequencies of energy)? Could things moving faster than light BE what we now call dark energy? If so would these bandwidths be concidered dimentions? Apparently dark matter may be operating at exstreamly high tempretures (no unobsevable radiation) & unobser…