Classical Physics

In space, is there a physical pressure? http://hypertextbook.com/facts/2002/MimiZheng.shtml Is this link accurate? If in space, sweat can not even escape a human body, which is a physical pressurised body , which has acting force on the sweat to force out of the human body, why can sweat not escape? unless there is greater pressure? It does not make sense to me I can not understand why is it not P=F/E? And is it so hot in space, in sunlight, because there is no thermal barrier i.e Earth's atmosphere to protect you?

Dear Forum, I have run across a very interesting machine that I was wondering if someone might could comment on. It is a version of the Sterling Engine, that uses a turbine instead of a piston. They have just completed phase I testing, and say it was successful. Here is a link: http://www.kendersolar.com/ This describes the technology: http://www.kendersolar.com/index.php/The-solar-technology-of-the-Kender-Engine-Phase-1.html They claim that the energy extracted by the solar panel produces more energy than what it takes to drive the compressor to circulate the helium, and results in: "The system produces 39 kW of power (47 kW by the turbine, less 8 kW …

Hi all, this is my first post on the forum so please be nice. I have been contemplating a device that is remarkably simple but, at least to me, somewhat curious. We all know that if we bring two like magnetic poles together they will repel. Equally, if we insert a sheet of magnetically permeable material in the space between the repelling poles they will attract to the sheet. Please examine the above drawing (sorry it is just a rough sketch). On the left is a metal rotor that has slots cut in it so that it resembles a disc with metal fingers around the periphery. When rotated the fingers pass between the two opposing magnets that are fixed to levers. T…

What is heat? (i). Potential energy (ii). Kinetic energy (iii). The state of an individual particle/wave (iv). The state of an individual atom (v). The state of a collection of particles/waves (vi). The state of a collection of atoms, ie, a body (vii). Something else

Hello, I'm a computer programmer and although I do have education in classical physics including electrical courses and as well as practical experience with assembly and testing of UV radiation equipment, their power supplies and overall wiring, I'm surprised to realize I have no idea what is the purpose, derivation (experimental origin) and the meaning of Maxwell's equations as I can not recall to have used any of them for anything. This realization happened when I was supposed to simulate - model and visualize in 3D - the simplest electromagnetic interaction there is, between electric and magnetic fields from only two electrons/positrons, including the tracing o…

This is a purely technical matter. I have consulted a few textbooks on Optics and Photography, but found no clear answer. I hope someone in this forum will be able to help. As anybody who has used a camera will know, you can regulate the amount of light that falls through a lens in three different ways: - the sensitivity of the film (ISO-norm) or the sensors (digital cameras); - by a longer or shorter exposure (shutter speed); - a wider or smaller aperture. My problem concerns the last method. Obviously, the larger the aperture the more light will fall on the film or sensors. What I do not understand is how the field of view can remain u…

I’m having trouble with the conservation of energy analysis of a rising versus a non-rising airfoil. (The non-rising airfoil is held down in place and prevented from rising.) ---- When an airfoil moves horizontally the surrounding fluid moves more quickly over the top of the airfoil and less quickly under the bottom of the airfoil. This means the downward pressure on the top of the airfoil decreases more and the upward pressure on the bottom of the airfoil decreases less. If the (decreased) upward pressure on the bottom of the airfoil becomes greater than the weight of the airfoil plus the (even greater decreased) downward pressure on the top of the airfo…

The physics book I'm using gives two examples where one is a third law pair and the other is not. What is the reasoning that this example is not a third law pair: "The upward normal force from the table and the downward force due to gravity are not an action/reaction pair of Newton's third law."

An "Ice bomb" is made by filling a very strong iron container with water and freezing it. As water freezes it expands in volume exerting a force of some 100,000 pounds per square inch. The "ice bomb", usually a grenade shaped cast iron container, when frozen, will explode with tremendous force. If contained within a wooden box when it explodes, it will destroy the box. A conventional hot air or heat engine similarly utilizes the property of a gas that expands and exerts a force with a change in temperature. A gas is heated in a cylinder and the expanding gas expands and drives a piston. Could a thermal engine be constructed that utilizes the property o…

Sadly, no one managed to realize what are the units of this equation and point if there are any mistakes in this dimensional analysis: [math]F_{12} = \frac {\mu_0}{4 \pi} \int \int \frac {I_1*dl_1 \times (I_2*dl_2 \times \hat{r}_{21} )}{|r|^2} = \frac {\mu_0*I_1* \int dl_1 \times (I_2* \int dl_2 \times \hat{r}_{21} )}{4 \pi*|r|^2}[/math] [math]=> \frac {\mu_0*Q_1*v_1 \times (Q_2*v_2 \times \hat{r}_{21} )}{4 \pi*|r|^2}[/math] [math]=> \frac {4 \pi*10^-7_{N/A^-2}*1_C*1_{m/s} \times (1_C*1_{m/s} \times 1)}{4 \pi*1_{m^2}}[/math] [math]=> \frac {4 \pi*10^-7_{N/A^-2}*1_A*1_m \times (1_A*1_m)}{4 \pi*1_{m^2}} \ =OR= \ 10^-7_{N/A^-2}*1_{C/s} \t…

That’s the skepticism that has reached us through the Enlightenment. Those that refuse skepticism in the realm of science then, and denigrate it, and recklessly rely on an “Unquestionable Authority“, they are ultimately placing themselves outside of Science itself, and outside of nearly four hundred years of philosophy if not more. I am skeptical of both god and “absolute nothing" ....that doesn't mean that I don't believe god or "absolute nothing" could exist... Actually it is exactly the opposite..I believe that god and "absolute nothing" could exist... TRUE science(being open to ANY skepticism or falsification) though is the only thing that could possibly prov…

I was trying to explain an issue on another thread http://www.scienceforums.net/topic/93442-gravitational-waves-discovery-expected/page-3#entry906394 and I wasn't making much progress But on a site I found the effect I was trying to explain:http://www.sparknotes.com/physics/gravitation/orbits/section2.rhtml Now years ago when I had said that the reduction in the potential energy is always split, half goes into additional kinetic energy and the other half is lost as drag, someone called that the "RB Law". I think it was a known fact long before I found it out so does anyone know the proper name for this relationship? The Potential energy gets more negati…

Why did it work? GO HERE:

Okay, a man is in a train that is going 25 mph. If he runs at 5 mph in the train relative to the train he's going 5 mph. But relative to the earth he's going 30 mph (if he's running the same direction). So if light always goes the same speed, what is it relative to? If it's going the speed of light relative to the earth, then how fast is it going relative to the sun? or the other planets? How can we even classify speed at all? I'm confued, will someone talk some sence into me?

This post results from the problem posed in another thread: http://www.scienceforums.net/topic/88301-earth-what-is-the-real-age/page-6#entry861043 If two planets each 1/2 the mass of the Earth collide what is their terminal velocity? This would depend if one planet was falling toward the Sun so it could have a velocity over and above that caused by the mutual attraction. (So we will have to ignore this additional velocity in the meantime.) I saw one statement that said: https://books.google.co.nz/books?id=0iggAwAAQBAJ&pg=PA427&lpg=PA427&dq=potential+energy+planets+colliding&source=bl&ots=MQYOmb0bj2&sig=cLZQMP-V8pwzhPi220UakLldSVA&am…

Wavelength refers to the distance between two crests or between two troughs. Imagine standing on the beach and looking at the waves coming towards you. The waves can cover a long distance along the beach, let us call it their width, but that is irrelevant. What you want to know is how often they follow each other (frequency), how high they get (amplitude), and of course what we have referred to as their wavelength. Here is a genuine question: To measure the wavelength, we are told to measure the distance between the points on a screen of (monochromatric) light that has come through two or more slits. This is a horizontal distance, comparable to the width of …

I'm blissfully ignorant when it comes to fields. At school level physics, (a long time ago), the word was used widely, without any detail being thrown in. I took it to mean "field of influence" but the physics world must have moved on since then. A gravitational field is said to be the curving of space time. Is a magnetic field and electric field also due to curving of a different component of space time?

Alternative wordings/synonyms such as "disappears", "no longer exists", "vanishes", etc. may be substituted in place of "destroyed" (Carnot Reflections, Appendix A). When "heat" (as a form of energy transfer) goes out of a working fluid as thermodynamic "work", my understanding is that the working fluid undergoes a drop in temperature as a result. In other words, a change in the total energy of the gas (working fluid or air, in a hot air engine) is measurable as a change in temperature. If the energy supplied to the engine in the form of heat goes out of the engine in a different form (mechanical motion of the piston, flywheel, etc.) Then the energy that fo…

So the electrical engineer who was doing this stuff for 50 years is wrong. The electrical engineer who solved computer crashes created by static electric discharges is wrong. Electricity only exists when a positive and negative charge make a connection. That negative charge cannot be created without creating a positive charge elsewhere. So when we prevent static electric damage, earth ground appears nowhere in that solution. Static electric prevention is always about making that connection from positive to negative charges via a path that is not destructive. It is even a standard experiment in physics class. Using Styrofoam balls to repel and attract. Ea…

know that objects with the same surface area but different densities fall at the same speed in a vacuum. However, there is actually a big argument between me and my girlfriend, at the point of I feel like strangling her to death. I say heavier objects do fall faster (I provided calculations). She (appears) to think that this is nonsense and am full-of-shit and she knows better because she knows more about the topic and am just a uni student (She was my lecturer, before we started dating. Now shes just my bitch) I dropped a piece of paper, and a piece of cardboard with similar SA. The cardboard fell much faster. I could explain this by stating that heavie…

Hello everybody, The satellites revolve in orbit. Are they in orbit due to; The equilibrium between the centripetal force provided by the Gravity & the Tangential velocity of the satellite? OR Due to the 'catch me if you can' game played between the Curvature of the earth's surface & the Escape velocity of the satellite. Thank you

from the day one i started doing science there is one unanswered question.... whether the light has mass? so anybody has a answer!!! is dat true light has mass in partical nature phenomena like compton effect,photo electric effect?

This has been a common trope running round most of the pop-science channels on Youtube over the last year or so. I won't name names but I guess some of you know some of the channels in question. It starts with a box with N particles randomly dotted around inside it. The presenter then changes the cartoon to one where all the dots are shown on the left hand side of the box and states 'Statistical Mechanics says that all random configurations of particles are possible, therefore sometime eventually this low entropy configuration will occur, therefore the 2nd Law only applies sometimes'. Leaving aside the macroscopic shift in centre of mass that shows dereliction …

I figure "magnetic lifter" was appropriate name for this problem. The question is: "What is the total Lorentz force on all currents? Is my math correct for total force on all currents?

[math]\text{Since light has energy, there is a small amount of mass equal to that energy.}[/math] [math] Given: f=1.0\times10^{15} \text{ Hz}, h=6.626\times10^{-34} J\cdot s, c=299792458 \text{ m/s} [/math] [math] Find: \text{mass of photon } m_p [/math] [math]E=hf, E=mc^2[/math] [math]\text{Equate the 2 values of E:}[/math] [math]hf=mc^2[/math] [math]m_p=\frac{hf}{c^2}[/math] [math]=\frac{\left(6.626\times10^{-34}\right)\left(1.0\times10^{15}\right)}{\left(299792458\right)^2}[/math] [math]=7.37242\times10^{-36} kg[/math] [math]\text{Compare with mass of electron }m_e=9.10939\times10^{-31} \text{ kg}[/math] [math]m_e/m_p=123,560[/math]