Classical Physics

OK ! First take a look at this picture : Basically, what I want to know is, how can I determine the minimal mirror's length so that the observer (blue smiley) can see the whole reflected image (reversed moon)?

Hi, I was wondering on the way light reacts with mirrors when the mirror is thick... Is it the image on the left or the image on the right?

I'm a newbie, so this may seem basic to many of you, but here goes. Does the moon's pull affect the law of gravity? (I'm thinking since the moon's pull affects the tides, perhaps it also affects gravity to the slightest degree?) Or are those laws constant, independent of the moon's pull? If so, how are these laws affected? Thanks

Why did it work? GO HERE:

Hello all, I have a slightly technical question. I'm trying to solve a problem on a stream (vertical jet) of hot water cooling in air (think of pooring tea). I want to compute the temperature of the water as it goes down. Now, since the water is accelerating (free fall), the speed of the jet is different in different places, and so is the heat loss. However, I do not know the dependence of heat loss on speed. Assuming the flow of air next to the stream is non-turbulent, I tried solving the heat equation, but with only one boundary condition (the stream/air interface), I spinned my wheels a bit and gave up. Is there a reference on this dependence ? It must be a …

Is this possible or not?

Hello, I was wondering, would it make any sense to try to get electricity from the IR part of the Sun's/Earth's radiation spectrum ? IR covers a very broad region of wavelengths, is emitted day and night, detectors are pretty cheap (they're the ones on your TV set) ... but there must be a reason people aren't really considering them. Thanks, McCrunch

Hi it's been a long time since I last logged in. I have a really important question: Is the magnetism around a magnet of the same sort as the magnetism around an electric line?????? If you don't understand my question just tell me.

So here is the question, Light is a EM wave, but a wave is a disturbance, and a disturbance is what something is doing, essentially action. So how can Light be a action? Or am I missing something here?

Can anyone please give me a site where they will give me schematics for a radio controlled transmitter and receiver.:-)

the things we hear that if an object can travel the way einsten explained e=mcsquare, is it true that it will affect the time either it will go to the past or the future and that the object can travel throught objects what do you all think please give your suggestions:-):-)

I have been wondering what does happen in the bermuda triangle is it some sort of extra gravity or any tornado and if there is a tornado what is causing it.please people give me your suggestions on what could happen there

can an infrared transmitter send signals to the infrared receiver if an object is in the way? Please answer my question and give me a suggestion whether i should use radio control system or infrared system for the car i am building.

Hi, I'll start by stating my intentions. I'm looking at buying a water pump to power a vacuum aspirator I have bought (link) and I want to make sure it can put out 30 psi so I can get a good vacuum from it. At the moment I'm looking at the water pump located at bottom of https://cheappumps.com/products.php?al=inpumps. It says it has a flow rate of 130GPH. My question is, is there any way to determine the pressure from this? It seems that there must be some way, but my understanding of physics is curently limited (just taking high school physics now). Any help would certainly be appreciated.

If work is Force x Distance, what is Force x Time? Example: you're holding a large book mid-air, eventually you get tired from it -- yet no distance was covered. But since a force exerted over a measure of time doesn't fit as "work", how's it result in spent energy? What's the term if no distance was covered? --Power? Effort?

I have been an electronics technician for nearly 60 years and an amateur astrophysicist for 6 years. It is my hope to divulge some discoveries only after discussing the rationale that pegs my theories to mainstream science even though conclusions might be surprising to scholars. My first focus is upon the Faraday cage, not for its utility against electrical interference, but for its influence upon ions developed within. Any isolated host might serve as a Faraday cage whereby any excess of one polarity of charged particles would be harbored upon its most outer surfaces due to mutual repulsion. Within limits, gravity alone would sufficiently hold some charged parti…

Why do some metals work in the microwave? Steel can be put in the microwave without the 'light show' as well as a few other metals. Whats the difference between these and aluminum?

I just read the thread about the color of the sky not being blue. I was going to add this comment but the thread was closed. I am surprised that no one mentioned the fact that Yes, the sky may not be blue. Color is only what our eyes perceive because of the wavelengths being reflected back to our eyes from the object. Newton observed that color is not inherent in objects. Rather, the surface of an object reflects some colors and absorbs all the others. We perceive only the reflected colors. Thus, red is not "in" an apple. The surface of the apple is reflecting the wavelengths we see as red and absorbing all the rest. An object appears white when it reflec…

I came across this in my physics book when discussing friction:- "If the wheels of a car are rolling normally without slipping or sliding, the bottom of the tyre is at rest against the road at each instant; so the friction force the road exerts on the tyres is static friction." Does that mean that when I'm travelling at say 70mph in my car the bottom of each tyre just for a fraction of a second is at rest with respect to the road surface? If so it must be for a very very short period of time!!

Hi. How is acceleration [math]a[/math] written in spherical coordinates, so that [math]a[/math] is not dependant from time but from the line element [math]ds=\sqrt{dr^2+r^2d\theta^2+r^2\sin^2\theta^2d\phi^2}[/math] So I would like to have [math]\frac{d}{ds}[/math] instead of [math]\frac{d}{dt}[/math] in the next equation:

When reading about energy, I'll better visualize what's going on by adding the word "transfer" to it. For example, I'd reinterpret "plants need energy from the sun to live" as "plants need energy transfer from the sun to live" "It generates energy in the form of heat" becomes "It generates energy transfer in the form of heat" Is what I'm doing accurate? Seems to me that "energy" and "energy transfer" are being used interchangeably in many cases. However, the type of energy situation needed to get things done, I believe, is only energy transfer -- as it'd do nothing otherwise.

In my physics book it has the following 2 equations:- F(subT) - m(subE)g = -m(subE)a F(subT) - m(subC)g = +m(subC)a To get rid of F(subT) it says to subtract the first equation from the second. here's where I get confused, I was to told (years ago) do this change the signs of the bottom equation and then add both equations but when I try that I don't get their answer of:- (m(subE) - m(subC))g = (m(subE) + m(subC))a --------------(3) Could anyone describe the process, as I don't get what's on the right hand side of equation (3) Thanks

What is the speed at any point of a path [math] \theta = \theta(\phi)[/math] on a rough sphere. The forces that affect the moving of a point particle are the force of gravity and the force of friction. I tried this way but I am not sure if the normal vector is right: [math] \mathbf{T}=\frac{dx}{ds}\mathbf{i}+\frac{dy}{ds}\mathbf{j}+\frac{dz}{ds}\mathbf{k} [/math] [math] \mathbf{N}=(-\frac{dz}{ds}-\frac{dy}{ds})\mathbf{i}+(-\frac{dz}{ds}+\frac{dx}{ds})\mathbf{j}+(\frac{dx}{ ds}+\frac{dy}{ds})\mathbf{k} [/math] [math] F_g = -mg \mathbf{k} [/math] [math] F_n=|\textbf{F}_g\cdot\textbf{N}|=|-mg (\frac{dx}{ds} +\frac{dy}{ds}) \textbf{k}|=mg (\f…

A 3 blade turbine, and a 12 blade turbine; being both the same diameter http://econewmexico.com/system/files/images/wind-turbine-wind-mill.jpg Which one is more efficient, can produce more power ? There has to be other variables as blade pitch, blades area, speed... even temperature... What formula applies to find out the power that can be extracted from a given wind speed ? Asking this because a large count blades turbine presents a larger blockage and reaction to wind than a 3 bladed one as the modern turbines are designed. There has too be other economical and construction factors involved to choose one or the other, but as amount of wind capture, one…

Have a look at this page: http://www.howstuffworks.com/horsepower1.htm Just before the "Torque" infobox, it states: "[...] convert torque to horsepower you simply multiply torque by rpm/5,252." After the infobox, there is a curve rpm/(hp & torque) which clearly doesn't demonstrate a linear relationship. I am guessing that the torque goes down (as the rpm goes up) due to the fuel mixture not exploding fast enough as the piston already is moving down due to flywheel inertia. Is this correct? If this is so, then the increase in hp as rpm goes up is less efficient that when the torque is high, right?