Classical Physics

Assuming a spherical body, is the gravitational acceleration at a given distance from the sphere's center, independent of the body's volume? For instance if you were orbiting the Earth, and the Earth suddenly shrunk to one tenth of its volume, would you continue to orbit?

My physics text asks "At what depth below the surface of a lake will you experience a pressure twice the pressure you experience on the surface?" I'm guess if at sea level, the amount of pressure in atm exerted on me is exactly 1 atm. So if its at 2 atm, there should be 2(760) torrs as well? So 1520 torrs = 1560mm Hg? Where do I go from here, I guess I can't use pV=nRT because it only applies to ideal GASES

When there are two current-carrying wires are put together facing the same direction on the same plane going through a paper perpendicularly, what will be the magnetic field observed on the paper?

any body got any ideas on how to make electrical wires superconductive and keep them that way? I was thinking that there would be a sleeve of liquid nitrogen around the electrical wires, with an energy absorbing system that used the thermal heat in the air around the wires to keep and produce more liquid nitrogen. any one got some krazy ideas? ( i know i spell crazy wrong)

a thought occured to me just during a coffee break, I could see the cup on the table and it`s shadow, it`s shadow was longer (taller) than the cup but proportionaly the same. now I`m wondering if you shine a light along a surface at a very gentle angle (like you`re 50 foot tall shadow at Sunset) the tinyest of details would be amplified along that axis several time, take a look at how long your shadow is at sunset and then stick out your finger, it may cast a 1 foot long shadow, and your finger maybe only a quarter of that length in reality, so right away you have a 4X "magnification" so with a proper light source and surface to shine it on at an angle, could this be us…

what type of engine is the most efficient?

you have a rifle and you have a target, with the bullseye at the same height as the barrel, that is 50 m away, calculate the angle at which you need to fire the gun to get a bullseye.

Hello, I'm new here. I'm wondering if anyone could help me find a technical term. It's for the action imposed on a body as it's sucked down into liquid (water) by the action of a larger body sinking beneath the surface. My enquiry has been related to the rapid sinking of a ship, and a maritime description of this, but I've been unable to find anything.. Any help for a not particularly scientific mind much appreciated! ao

Hi all, I have a quesiton about how we measure vibration. I am developing a keypad that provides haptic feedback, for this i am using vibrator motors not too dissimilar from the vibrator motors you find in mobile phones and pagers. such as http://www.vibratormotor.com/4AL-01WA.html and http://www.sanyo.com/industrial/micro_motors/vibrator/downloads/4L-M-01-080.pdf I would need to include a metric for vibration in my study design when evaluating the suitability of such a device. In these specs it notes the motors RPM but this isnt actually a metric of vibration, e.g. amplitude and displacement. Is there a standard metric for measuring vibration? if so is …

Im a highschool student who needs to build a catapult for my physics class, there arent any specifics to the build of the catapult(no air cannons) but it just needs to be able to launch a superball 2 meters. I was wondering if anyone could offer me some advice on a good design to use, i was thinking of a trebuchet but i think that might be to difficult to build on this fairly small scale. Like I said other then compressed air, anything goes.

I was wondering. How fast does an object have to go before the human eye can no longer keep up with it?

I want to ask something about voltage. Referring to the figure, there's no drop of P.D. across E ,D through EFD. But, through EDCB, there's a P.D difference between them. The voltage across E and D in fact= e.m.f. But why we neglect the first approach? Can anyone reconcile the two approachs.

Hey guys, I just made a website, and I wrote an article regarding the nature behind gyroscopic motion. Would some of you care to read it and see if it all makes sense or if there is something you would like me to include? Thanks the site is http://www.thehowandwhy.com/Gyroscopic.html

What is the proper way to find them? I believe that my physics teacher is wrong on this, and I would like to find the correct answer.

Here's the problem: A 500g steel block rotates on a steel table while attached to a 1.2m long hollow tube. Compressed air fed through the tube and ejected from a nozzle on the back of the block exerts a thrust force of 4.0 N perpendicular to the tube. The maximum tension the tube can withstand without breaking is 50N. If the block starts from rest, how man revolutions does it make before the tube breaks. Now back of my text book tells me its 3.75 revolutions But here's my solution: I approached to this problem via the rtz-axis, (Fnet)r = Tension of hollow tube = mass*w^2*radius (w, for angular velocity (Fnet)t = Force of thrust = mass*(accelerat…

Just thought I'd get your thoughts on this. Is the earth overall losing energy. It loses energy from tides, however the earth-moon system remains at constant energy. Our magnetic field is losing energy. Are we losing energy in our rotation? We gain energy from the sun but is the loss of this heat energy more or less than our gain....? All responses welcome

Sorry if this thread doesn't belong here, but I didn't know exactly which branch of physics it belonged to. So anyway, I was taking a placement test for a science club at school and one of the questions went something like this: "A pilot of an aircraft is flying over the ocean, when all of a sudden, he accidentally releases his explosive bowling ball. To avoid wasting a good bomb, he detonates the accelerating ball in mid-air and it bursts into exactly 1000 identical pieces of 10g each. Surprisingly, the blast generates neither sound or heat. Explain what happened." Anybody have any Ideas?

below is what I discovered.. If you heat up the water up to 100c, ie, it is boiling, the temperature no longer rises further... I know the reason can be explained on the kinetic and potential energy of water molecules, but I just dont know how... any body?? thx

http://www.muchosucko.com/video-magicbubble.html ??? (ps the site may have inappropriate advertisements or whatever so... NSFW, its one of those stupid video sites)

I would like to know which factor(s) is(are) essential to find out a focal length between an object and a lens. And the distence between the object and the lens is known.

any ideas on how to find the average acceleration of the earth moving around the sun for an eight month time interval?

I originally posted this in a different section, but i think its more appropriate here. I was lying in bed last night when an interesting idea struck me, however, it revolves around 1 important thing; I need material capable of completely blocking a magnetic field. Bismuth is something tht i have considered, as it is diamagnetic, albeit weakly, but any other suggestions would be greatly appreciated. Also, is bismuth "complete" in its diamagnetism? i.e will it completely reverse the magnetic field, so even though the reverse field will be weak, there is nothing left of the previous polarity? i hope i made that clear enough :s heres a picture to demonstr…

Ok... let's say you have a mass of 1kg, contained in a single point. by the equation: [math]F=-G\frac{m_{1}m_{2}}{r}[/math] the smaller the r, the larger the force... In fact, [math]\lim_{r\to 0^{+}}{F=-G\frac{m_{1}m_{2}}{r}}=-\infty[/math] So, that means that any mass, if you're close enough to it (as in, like a trillionth of a nanometer) the force will be so great that once again, light would not escape it and an event horizon exists that is astronomically small. Is there something I'm missing here or is this true?

Ok, I have a question about a simple, but not so simple, system. Let's say I have two rigid, massless poles of length L, joined by a massless, infinitesimally small motor that exerts torque T. If the poles are parallel, and I stick one into a concrete wall for anchoring, obviously the motor will move the free pole. Plus, if I push down on the tip of the free pole, I should need TxL newtons of force to prevent movement. That's simple enough, good old levers and such. But what if I attach another motor to the tip of the free pole, and another pole to that motor, so I have 3 poles in a line, joined by two motors? (another way of imagining it is like your arm, bend…

Sorry for being so abrupt but I am doing this for a GCSE Project. Could anyone maybe explain what this is all about? Thank you, you clever people.