Classical Physics

Hi all, I am probaly having misunderstandings about the working principle of hyperbolic funnel for educational experiment of gravitational force. Wikipedia says: "In a uniform gravitational field, the gravitational potential at a point is proportional to the height. Thus if the graph of a gravitational potential Φ(x,y) is constructed as a physical surface and placed in a uniform gravitational field so that the actual field points in the − Φ direction, then each point on the surface will have an actual gravitational potential proportional to the value of Φ at that point. As a result, an object constrained to move on the surface will have roughly the same equation of m…

I am a bit confused by this question(see attached image). This has been posted before but im not any further forward. My problems are: P1 - has this got the following forces acting on it: Weight, Tension, and Natural reaction force? and thus does the equation of motion end up as: mr''= -|T|er - (mgcos a)er - (mgsin a)eo + |N|er where er and eo are the radial and tangential components respectively Then is it a case of gathering the similar terms and resolving in the er direction to get: ml0'^2 = mg cos a - |T| P2 - is this just experiencing the tension of the string and its own weight?

Inspired by the Tour De France I have been running a poll on my local cycling group website asking whether a 'heavy' bicycle rider would roll down a hill faster than a 'lighter' rider. Assuming the two riders (one 50kg, one 100kg) are on identical bikes and are stopped on top of hill then roll down the hill with no pedaling and no brakes and no corners to negotiate who would arrive at the bottom of the hill first and what physics principle would be involved ? My cycle mates swear 'black and blue' the heavy rider would get to the bottom first. Thanks in advance, kevinc

I'm unofficially taking a course in the gradute Classical Mechanics this semester. The text we are using is Classical Mechanics - Third Edition, by Goldstein, Poole and Safko (2002. I'm trying to solve Exercise 17 in Chapter 2. The problem reads Where reduced to quadratures means expressed in terms of definite integrals which can be evaluated analytically or numerically. I can't see how to do that. I'll post the differential equation that results when one uses that Lagranian L = T - V later tonight. Thanks in advance. Pete

A video camera in an air filled underwater housing is ballasted to be neutrally buoyant. Does not sink, does not float. Will removing a 200 grams (dry) ballast weight from inside the housing result in a more, less or equal amount of flotation if the same 200 grams weight is removed from ballast attached outside (wet) ? Miguel

We are told that "The action and reaction forces between a pair of interacting bodies are of equal magnitude and are opposite in direction" So if a locomotive exerts a force of say 10000N on a wagon (via the coupling) we know that the wagon exerts exerts an equal force of 10000N on the locomotive in the opposite direction, why then does the train move? Doesn't each force cancel each the other out?

If I know the distance an object travels from point A to point B, that it starts from a stopped position and the time that it takes to get from point A to point B, how can I calculate the top speed at point B?

Hello, Could someone please explain how to describe the collision between two spheres (in two dimensions, for simplicity), if friction is to be taken into consideration. Since the collision happens instantaneously, I suppose the most useful / correct way to describe it would be to use impulse rather than force. cheers, Michael

[math] W = \Delta Ec [/math] [math] F. \Delta x = \frac{mV^{2}_{f}}{2} - \frac{mV^{2}_{o}}{2} [/math] [math] m.a. \Delta x = \frac{mV^{2}_{f}}{2} - \frac{mV^{2}_{o}}{2} [/math] divide by (m) on both sides [math] a. \Delta x = \frac{V^{2}_{f}}{2} - \frac{V^{2}_{o}}{2} [/math] [math] {V^{2}_{o}} + 2.a. \Delta x = {V^{2}_{f}} [/math] [math] {V^{2}_{f}} = {V^{2}_{o}} + 2.a. \Delta x [/math] Just to show that everything we learn in physics at school is actualy 1 thing Dynamics, Cinematics and etc Isn't is beutiful! (forgive my english)

Hello everybody! Is there any difference between a torque and a moment? Both are forces multiplied by the distance. Thanks!

Physics hasn't been a part of my life since I graduated from high school. Now I got this great game "The Incredible Machine: Even More Contraptions", I'm starting to remember it all. This game doesn't seem to require any calculations, but the player has got to understand how the things work, such as pulley, teeter-totter etc.. The game interface is a little similar to the Electronic Circuit Design and Simulation Software that I used. I'm just hoping someone professional has played this game and tells me what you think. Is it an accurate "simulator" for real life physics? P.S. There is a "glittery" ball that bounces forever. I don't think that's possible in re…

The mechanics of gravity. Most of us have wonder about the magnificent workings of gravity and have at some point or the other asked the question, how does gravity work? Through countless people, and have only ended up with the age old mathematical answer, in this age of information where information is abundant, even the most innate theory of the mechanics of gravity is impossible to find. Which leads to the conclusion that either the Symantec search is invalid or that no such theory of gravity even excites. Gravity The FORCE that attracts two objects to each other in space. (Which force and why is it present?) Most will agree that they must be s…

Just a quick question as to WHEN this law can apply to objects... Is it applicable when two objects are REALLY close to each other? I saw this question asking what acceleration a person experiences when he is inside the earth. Is it even possible to calculate the acceleration?

For an understanding of magnetic fields and waves, as they are relevant to typical electrical sciences (and perhaps to some degree light) I was wondering if a knowledge of calculus should be all thats necessary to understand the mathematical aspect of it. On that note, if I am to understand Einstein's papers, what else should I learn? I'd like to know what other maths I should pursue to have a decent grasp of the above things.

Simple: What happens to the magnetic fields of two opposing north sided magnets when pushed ever closer to each other? Visual description, haha: >S/N>--?--<N/S< Thanks!

Hi, I have been reading extensive physics of my educational curriculam. I am not good in learning concepts. But i can undertand it. How come theoretical studies taught in physics have a big importance! When it comes to building something, i couldn't even search and mould wood for contructing huge mechanics! The wright brothers for example were private enthusiasts who collected and contructed a thing which could fly in the air! I was thinking if it were possible that a ferrari car dissassembled into bits and pieces. And then it was given to science students for remaking it! Would the science students be successfull? Or would they need theoretical lecture? So…

I read about the second law of thermodynamics just yesterday, and I HATE the concept of entropy. My textbook says that entropy is the disordered energy (or heat, right? does it only include heat?) in a system. It gave me this formula: G = H - TS which is supposed to mean: Free energy = Total energy - (Temperature in K)(Entropy) But how would a scientist quantitatively measure entropy to use this equation? Or is the equation just a way of explaining the concept and not meant to be used? Anyways, what really pisses me off is the fact that they describe "entropy" as "disorder" or "randomness", when I always thought scientists would know better th…

Hi, I am hoping someone can help me with these equations: If two ping-pong balls were dropped simultaneously onto a completely flat surface of water, the waves from both balls would propagate radially outwards until they met, where their amplitudes would superimpose exerting a force of attraction on the two balls. What equation/s would describe the force exerted on the two balls and allow me to discount any loss due to the viscosity of the fluid? What equation/s would describe how the radius of the propagating wave would be proportional to its' amplitude? Thanks. In relation to: http://www.scienceforums.net/forum/showthread.php?t=33431

I was trying to explain to a friend of mine why the time it takes for one swing of a pendulum is independent of both the mass on the end and the distance it is drawn back (for small angles, of course) but could not for the life of me remember the derivation of the equation for period of a simple harmonic oscillator [math] T = 2\pi\sqrt{\frac{-x}{a}}[/math]. Could someone help me out with this?

I have a few questions concerning the Faraday cage. As I understand it, the electric field inside a cage build from a conducting material, is zero. Does this mean that the sum of electric forces acting inside the cage is also zero, or are there simply no forces at work? The conducting material opposes outside electric fields, by aligning the electrons in such a way, that the electric field inside is zero. But what if the total number of electrons in the cage, are not "enough" to oppose the outside field? That is, if a very strong outside field is applied, how can a limited number of electrons align to oppose the field? And finally. The cage can be a grid, or…

For the longest time I have been trying to figure out how far a projectile will go after being launched from an air cannon. I'm trying to figure out how big of an air chamber I will need to build to shoot a certain object so far. I was looking around and found someone saying that PV=1/2mv^2 gives a good estimate, but I wasn't too sure and confused about when solving for v, you're only left with a length(I think). So I am wondering if someone could help me figure out either what the velocity of an object would be as it's leaving the barrel, or how far it could go. The pressure of the air chamber, volume of air chamber, mass of object, area of object, length of bar…

Hi, I never understood locomotive traction! It was in my study. How come metal made wheels of locomotive are made to stop on metal rails!?? I prompted my lecturer, he told me about magnetic brakes! But i didn't got the answer that i really wanted! Metallic heavy locomotive with a huge momentum is made to stop on rails which have no friction between them! Or is the magnetic brake just an alternative in clamping down the speed of the wheel movement! If you ask me, the locomotive should never stop! ------------- eric

Hello all, I'll get straight to the point. I've been trying to write a program that would simulate the movement of stars, and I've been having slight problems in thinking up the most fundamental part of this idea: the way gravitation interacts with those stars. Here's some basic info on what I need, how I need it, and how I've been trying to solve the problem. Every star (I'll be calling them objects) has it's given mass, position, and velocity. We are in Cartesian space. Since I'm using C as a programing language, I have no choice but to represent the velocities and their directions as X and Y speeds. You probably have no idea what I mean, so let me explain on an…

Hello all, I have a question. Further information on why I'm asking can be found at this yet unanswered post.My question is; If I have a stationary object one of mass x, and a stationary object two of mass y, do I calculate their displacement using [math]F_g = G \frac{m_1m_2}{r^2}[/math] or using [math]a_1 = G \frac{m_2}{r^2}[/math] and [math]a_2 = G \frac{m_1}{r^2}[/math] ?? I thank anyone willing to shed some light on this confusing matter. Shadow

If you construct Newton's laws in a rotating system, does a centrifugal term fall out?