Classical Physics

Another post has made me want to develop a better understanding of waves in general. Does anyone have an approach to remembering everything there is to know about waves? I need a referesher. 1. Transverse waves 2. Longitudinal waves 3. Compression waves (longitudinal synonym) 4. Shear waves (transverse synonym) 5. Standing waves 6. Traveling waves 7. Spherical waves 8. Plane waves 9. Beats All waves have what in common exactly? It's one thing to understand the sine function, or cosine function, its something totally different to understand a sine wave, or a cosine wave, in which you have the medium changing in time. There are density changes, and…

Just wondering.

Hello everyone, Today I saw some waves in my physics lessons. A stone drops into water, and waves are created and spread from source to surroundings. Finally, the water became calm again. What's the most proper explanation for that? I think: Water molecules gain energy after being hitting, they collide the others. By law of conservation of momentum, it is rather obvious to see the total amount of kinetic energy decreases after a collision. Finally, it becomes 0. Is my explanation correct?

Have been watching the world is not enough and i noticed that they handle small amounts (2lb etc) of Plutionium, claiming this small amount will do no damange to you. Is this true?

So let's say I want to make a double parabolic mirror (like the one at http://www.optigone.com/ ) that recreates a virtual image of a three dimensional object. That in itself wouldn't be too incredibly challenging. It's also entirely possible to do so. But is it possible to enlarge the virtual image using nothing but the shape of the parabola(s)? Or, if not, then the parabolas and a lens? While I'm on the subject, how do those devices work? I know that they just reflect the image back up to a different focal point, but what is the physics behind it? Specifically, how is the virtual image created, and where are the focal points of the parabolas?

I know this is going to sound like a stupid question, but is inertial mass a scalar or a vector? Another question I have is, what is the definition of inertial mass? Is there an operational definition for it? Thank you

We all know that momentum and force is related particularly but when it comes to reality, how can we set up an experiment that shows force, momentum, and acceleration, that is practical enough to be calculated and experimented??? I mean, there is friction, air resistance all over on Earth... It comes to me that those ideas become so theoretical rather than practical Any help?/ Albert

I find something contradictory to these two questions and there answers.... 1) A breakdown truck tows a car of mass 1000kg along a level road, and accelerates 0.5m/s/s. What is the tension in the towline??? Ans: 1000/2 = 500N = the tension 2) A trailer of mass 1000kg is towed by means of a rope attached to a car moving at a steady speed along a level road. The tension in the rope is 400N, why is it not zero???? Any idea to the question in bold???? thx Albert

I have recently become interested in inertial guidance systems, specifically I want to know the physics of how they work. Assume I know nothing and go from there. Thank you

What causes two objects to collide? How come when two objects collide, they apply a force on each other, and either stop or move in opposite directions? Why don't they just go through each other and keep moving? When programming a video game, nothing happens on its own. If you make two objects move, they won't collide unless you write a collision code and put it in the game. Without a collision code, the two objects would go through each other without causing any interference with the movement of the other object. What creates the collision code of the real world?

Why we cant express Work interms of Momentum??? One is F*d and another F*t..... Albert

Hi, here is my question... Two cars travelling toward each other each at the same velocity (100km/h). They collide head-on. What speed to the passengers leave their seats? Does the weight of the cars have any baring on the answer? Please discribe which laws of physics support the answer. Thank you.

The first of my two questions regarding lasers and the like is relatively straightforward. Is there any way to make a system in which two lasers with frequencies in the non-visible range intersect to produce visible light at their point of intersection? The only way I would think this would be possible would be by having one laser in the infrared range and another in the ultraviolet, and somehow getting them to combine in a way that produces a point of visible light... I'm not that knowledgeable in physics, so I don't know how absurd that sounds (hence the question), but any answers, whether affirmative or not, would be helpful. Along the same lines, given th…

Not relevant... read below.

Given the following situation: A clear, colorless liquid is contained within a double-parabolic mirror that is constructed in such a way that anything placed inside will be reproduced as a virtual image above the two parabolic mirrors, AND the liquid is excited by an ultraviolet laser and, as a result, fluoresces... Will the virtual image be distorted because of the liquid? In other words, will the liquid bend the light emitted by the excited particles?

Imagine a jojo. You hold the end firm, and let it go. It falls down, gaining linear speed and angular speed. Forces acting on it is G due to gravity, and F due to the string tension. What I am wondering is this: How do you prove that the F in the equation "F*r = I*\omega" is of the same magnitude as the F in "G-F = m*a"? Since F act normal to the radius, and not through the center of gravity, I dont find it that obvious. Should it be obvious? Thanks

Thank you.

A certain star has two planets and the "year" of one of them is 3.4 times the other's. One question could be how much farther away is one than the other but to complicate matters I wont ask that directly, but will talk about "equilibrium temperature" on the nearer planet the equilibrium temperature is just right to boil water at what we think of as normal atmospheric pressure. equil. temp. is how hot a dark surface facing direct sunlight will get (one thinks of it as back-insulated so it has to get hot enough to radiate away same amount of energy as incoming) have to go. my question is what is equil. temp. at the farther planet?

Imagine a planet that is so small and unmassive that, even close in, the orbit speed is only 6.7 miles per hour (if there were someone running, they could keep up with you, or more precisely the runner would go into orbit as well) perhaps it has a specially benign atmosphere which offers no air resistance but it good to breathe and is a comfortable shirtsleeve sort of temperature maybe it is spring and you can smell plumblossom and magnolia and you are in orbit just grazing the hilltops, seeing everything on the planet at the speed of a run. You are invited to calculate the mass of this planet, just from one additional piece of information. In an orbit with a…

Ok, I have a question...if you could stop time, or if time stopped, would gravity stop, too? Because in movies, (I'm not saying movies are always right ) whenever time stops, water and stuff freezes in midair, but the people can jump through it and land on the ground. (Of course, it might be that gravity is always there, but it doesn't...act on you...if...time is...stopped? I don't know. What do you think?

What is the difference between mass and matter?

hi, i've heard that water drains down a plug the opposite way in australlia than it does in the uk, but what happens if you go to the center of the earth.. withh the water just fall directly down?

I have a question about jet boats or personal water craft or jetskis or what ever you like to call them. It concerns the water jet propulsion unit in the back of the boat from which water exits as a jet stream and moves the boat forward. One of Newton’s laws at work here I believe. My question is: With an equal amount of power supplied to the system, forget about drag etc, is it better to have the water jet propulsion unit above the surface of the water or below it? Another way to put this is, do you get more measurable thrust, with the same amount of power applied, with the jet above the water surface or below the water surface?

I think this belongs in one of the mechanics threads, and I'm pretty sure it fits here, but feel free to move it. Anyways, I know that things like radio waves, light, and microwaves all fit under the Electromagnetism category. I'm curious to know what fits under the same category, so anyone interested in making/contributing to a list would be welcomed. Also, if someone could give me a basic reason why these fit under the same category, that'd be nice. I'll try my best to understand it. Plus, are there ways to convert between these forms? Can you, for example, convert radio waves to visible light? Or could you possibly piggyback these things, like by (ignore practi…

Is electricity formed when one or more electrons of an atom is/are moved?