Physics

Hi! Does anyone know a good, controlled method to test the tensile strength of hair? Thanks

From the earth's surface, on a clear night, what is the equivalent temperature of the night's sky? I notice that (as I expected) water will freeze (shell) over in a bucket at +2 C when I am watering my rink at night. When it is overcast at night I wait until it is below freezing. I'm roughly at sea level. Obviously the water is evaporation cooling and radiating more than it is receiving radiation and conduction in order to do this. I know it is not as cold as 2.7 K because the clear atmosphere is "clear" in the visible range but not all of the rest. So what is the equivalent black body temperature of the open sky?

Could you design an explosive that spreads materials around the blast that aid to defeat it for a controlled radius? Such as materials that would consume blast energy in a certain period of time that act along with the explosive on explosion? I was just thinking it would be neat for instance if you could make a material like that you could have say firecrackers that have a square shaped explosion or what not, to more advanced shapes possibly? Maybe the explosive material itself could be modeled to reach certain phases like being a plasma possibly? As I don’t know if you could reach different results with various combinations of materials and engineering of the d…

OK, well I'm just working through some optics stuff I've got to do... And I've got to substitute into the Fresnel equations, for [math]\theta_1[/math] where the 1 is for transmitted and 0 is for incident/reflected. So here goes... snell's law: [math]n_1 \sin\theta_1 = n_0 \sin\theta_0[/math] square it: [math]n_1^2 \sin^2\theta_1 = n_0^2 \sin^2\theta_0[/math] subs in: [math]sin^2\theta_1=1-cos^2\theta_1[/math] => [math]n_0^2 \sin^2\theta_0 = n_1^2 (1-cos^2\theta_1)[/math] => [math]\frac {\sqrt {n_1^2-n_0^2 \sin^2\theta_0}} {n_1} =cos\theta_1[/math] Now that's all well and good, but n1 = n+ik, so which of these is true: [math…

having spent a year in the southern hemisphere my perception of earth and its rotation has certainly altered so i pose the question which way around are we all facing . given that the northern hemisphere is rotating in a anti clockwise direction and the south the opposite is there a definitive answer to my question the is no right and wrong way around . but having said that is the universe acting in that fashion is the equator the centre of our universe if we sliced though it like an orange do we end up with two pieces the same in which case is the two pieces acting in the same fashion . is time in relation to this acting in the same way . can someone give me a explanat…

Anyone know the exact date this thing gets turned on? Because I have just been trolling some sites with all these crazy probability of things going wrong, I know most of the hype is just for the sake of it, but im kinda with them on the fact no one can say 100percent that the only thing it will create is better graphs of particles hitting each other at nearly the speed of light, any maybe new unknown particles, but what if it does something crazy, which wipes us out in a split second..inno quantum shit scares me. It makes nukes and shiz:confused:

Why is it that when I switch on my 60W desk lamp the wheel in my electric meter spins fairly slowly but when I switch on my 2.5kW electric kettle it spins around like nobody's business. Presumably the potential difference at the wall socket is always 220-240V so is it something to do with the resistance of the appliance?

Hi I have a question about some theorical setup and try to understand how it will behave. The goal of that exercise is to help me acquire some knowledge of how to apply the electromagnetism math to concrete setup. All setup are in empty space (no air) where gravity is negligible, in a farady cage and magnetically sheilded. First set up made up with 2 non-conducting objects. - A point like sphere S of charge Q1 and mass m1 - A perfect ring O of charge Q2 and radius R and mass m2 The center of O is at the origin and lay on xy plane S is at a distance z on the z axis What will happen if we keep O stationary and let S go. It depend of the charge of Q1 and Q2. If the…

What is voltage produced by a galvanic cell made with carbon and magnesium electrodes, on a ClNa electrolyte; ? If the Mg is replaced with aluminium, what would be then the voltage generated ? What atomic data of the Mg, C, Al elements is used to determine/calculate the voltage generated ?

How can I receive a 50kV electric shock (say via a taser) and not get killed?

I was guessing it was in here. I'm not sure... I'm not really that knowledgeable on the classifications of science. I've come up with some ideas on time travel based on the notion of what speed to travel at to go backwards in time. Is this the proper place to discuss this? If not, where should I go? Thanks and sorry to seem like a dunce around here.

Hello, I am new to this forum and am not too experienced in physics. Thought I am currently taking Electronic Engineering courses, which is what bring me here. This is really more of a recommendation request than anything else. Basically I have a project coming along where we hope to achieve some success in sound cancellation. The challenge has proven very difficult so far, especially in open 3rd environments. I was hoping to possible get some ideas on books or any kind of resources that might be able to help me in this project. For instance I really need a good book recommendation on the physics of sound, and how it is distributed (Something light in terminol…

I was wondering... How would gold affect a magnet? Would putting gold underwater cause a great affect in magnets? Tell me in any way you can

what is the difference between a charge and energy? i dont much about this so i was just wondering because you can convert electricity [store it] and then use it for energy. like turning on a light bulb. i might be missing something here so please clarify

How is it called? It is shown usually in the Pacific ocean -for available space-, I believe has something to do with (solar?) declination trough seasons, it is an elongated "8" What does it mean ?

Please don't mistake me. There is a belief that if one person travels into a worm hole, he will go to future or past Is it possible??? please help me.

Not sure if any of you have seen this, but below is a youtube link so you get an idea of the variety of situations you can simulate / create... Here's a link if you wish to download (only windows and Linux)... http://www.acc.umu.se/~emilk/ I really should be in bed, but another half an hour on this won't hurt

I honestly don’t know if this is a simple question. Can something exist that has no thermodynamic potential or signature of any kind? I mean I was just thinking about dark matter/energy for whatever it is, and I don’t know for sure but I don’t think such has any thermodynamic anything to it right?

Quick question that has been bugging me for a while. I was looking into the recent discovery of a new 'Earth like' world, Gliese 581 c, which has a mass 5 times that of the Earth. However, its gravity would only be twice that of our planet. Question: Why is the gravity not 5 times as much if the mass is?

I need help with a science fair project. I will tell u briefly what i am trying to do. In a Science Fair, i need to prove that sound, radio, and light waves can be affected by destructive interference. I already have used my computer to lower the dB of a given sound wave by about 85%. I have taken one speaker from the computer and angled it about 10 degrees toward the other, and let one speaker play the opposite continuous tone as the other (at 350Hz). This works fine. Radio and light waves are much more difficult to do a demonstration for, so i hope that i can JUST prove the possibility of canceling them out using just math. I read that light waves are know…

This question comes from a thought I had in my physics lecture today. Lets say you have two of the same size conductors with two equal currents running through them in the same direction. Both of these currents would produce a magnetic field. Between the two conductors, the direction of the magnetic fields would be opposing each other. So between the two conductors, the superpositions of the magnetic fields should cancel each other out. Yet, in lecture, my professor said that there is still an attractive force between these two conductors. But, isn't the force dependent on the magnetic fields? Why is there still this force, when the magnetic fields should …

My friend Betelgese toldme this.(heisa member) Let us assume that the gravity of earth is1.Since the gravity of moonis 1/6, we are able to nearly fly in moon. Suppose, we go to a planet which has gravity 2 stay there for some years and then when we come to earth, would we able to fly in earth. Please help

Earth produces 1G - is this solely dependant on mass, or density as well? In other words, lets say I have a less massive object, with an extremely high density. Can that exert 1G on something very close to its center of gravity? or must you have as many atoms as earth regardless of density, to produce 1G? thanks

So, dark matter has gravity, but no friction? Doesn't that mean that it would be impossible for matter to clump together to form macroscopic objects? With the attractive force, but no impeding force, it would seem that a system of dark matter particles could be in somewhat of a perpetual harmonic motion. Is that reasonable?

hey, I found some academic notes, maybe many of you find it interesting: