Concept Definition and 1000 Threads

My first post here is going to be a question. Hopefully you guys can help clear this up. I simply have been unable to grasp the concept of voltage. I know how to calculate it and all but I can't grasp it. :bugeye: I know that: Couloumbs : the actual amount of energy Amps : speed...

in einstein's famous gravity model - gravity is caused by a disruption of some fabric by an object with mass (i.e. the ball on the fabric causes the fabric to "expand" creating an inward force toward the ball for other objects). i was thinking about this and wondering the following: 1) if...

Hey Mathwonk, just a quickie. When I think of a differential, it is written as y=y(t), and dy= dy/dt * dt. When I see this, I think of it as we want to deal with only the variable y. But y(t) is a function of t. So we set y=y(t), so that y is a variable by itself. As a consequence, we usually...

So what do you people think? What are the arguments for each?

A pole of scientists gives a surprising variety of opinions: Address:http://www.spiked-online.com/sections/science/sciencesurveyA-B/default.htm The one that stood out to me, in the context of PF, was: "Science is disputative." Alot of people echoed Feynman's answer to this question...

If E(cell) = E(cathode)-E(anode) and E(cell) = (RT/nF)ln K Then shouldn't E(cathode)-E(anode)=(RT/nF)ln k ? I have a question asking to find the voltage of the cell and I am given a equilibrium constant... which means i should use the second equation with "k" in it, and i get the...

I'm having trouble understanding the concept of laplace transformations. my book states that it is comparing how much a function y(t) is like a standard function. what exactly does the answer mean such as y(s)=1/(s-2) is this the differnence between the functions depending on the value of s...

Can someone explain the concept of recrystallization in metals to me? I'm having some trouble understanding what actually happens in the material during this process, and also what causes it to happen...

i hope everyone's in fine health in this fine thursday evening. :approve: ok i just had some general questions on atomic masses, and to the chemists in here, i appologize if these questions are a bit too basic for you. :cry: but ur help and time is greatly appreciated nonetheless! :smile...

If we want to prove any equation. How we come to know that when and where we have to put the value of this or that formula or when and where we use this or that formula? e.g. (Derive an equation which shows that the absolute temperature is directly proportional to the average translational...

The concept of "Rotation in 3-d" in QM I'm having difficulty with two ideas and wud appreciate some help: 1)commutation relations: [L_i, L_j]=i\hbar\epsilon_i_j_kL_k reflect the law of combination of rotation in 3 dimensions. What is the this law and why must in be satisfied...

Quick concept question! Ok, How does the current relate to the speed. So let's say everything is normal and if I reduced the speed by 1/3 what would happen to my current? Thanks! :cool:

Hi, Its been a number of years since I've actively studied physics, and I find my knowledge extremely lacking, however there are some fundimental concepts I seem to get lost in and would ask for some (polite preferably) assistance. My problem is with regards to dimensions and our (or my...

It is known that a tensor field is a tensor-valued function T=T(p) whose argument p is a point of some space (or some manifold). However, in physics some tensor fields are produced from other tensor fields, e. g. Lagrangians in physical field theories including tensorial fields...

How much energy is given out by one man? If he applied a F on a object, friction is f, distance is s. What's the energy given out by him?

I am new at here at PF and originally posted part of this in an inappropriate forum then added a few words and moved it here but didn't like it as it read so I deleted it and started a fresh thread. I was very tired and about to drop one night when I had a strange thought about where did...

Last we were introduced to the concept of entropy in school... I was quite suspicious to it already at first sight.. It is something like that in a closed system, chaos always increases... meaningen that universe is heading towards chaos... (i.e. universe is heading towards where materiai...

Thougt of a thing, reading a topic about dimnesions... if we think like this... a point had 0 dimensions... there are infinite many points in a line (which has 1 dimension) there are infinite many lines in a square (which has 2 dimensions) there are infinite many squares in a cube...

I want to share and discuss with every forum posters here a new concept on piston heads, which by the way is not as brainy as you may think. The new concept is concerned with spark ignition engines. Everybody know that combustion process have two main stages in this kind of engines...

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...

A negatively charged rod is brought near a suspended metal sphere. The sphere is 'grounded' by touching it with a finger. The finger and the rod are now removed. What charge will be on the sphere, positive or negative? Explain what happens. Initially I thought that the finger would remove any...

Consider a long conducting rod that is suspended by insulating strings. Assume that the rod is initially electrically neutral, and that it remains so. The rod is positioned along the x axis, and an external electric field that points in the positive x direction (to the right) can be applied to...

Consider the concept of a gyroscope. You tie a string to one end and attach the other end to the ceiling so only one end is supported, If you let go when it is not spinning, the obvious occurs - it falls from its horizontal position to a vertical position with the other end pointing towards the...

Have posted this in the philosophical section, but would be interesting to see replies from here, in a true conroversial style. the questions are: Does sin exist? What is your understanding of sin? Is sin the same as the concept of wrong? Where did your understanding of right and wrong...

i am ineterested in complexity concept do u know any introductory documan on net ...

Ok, Suppose I have two balls that come into contact to make their charges say q1=q2. Would the charges be equal if the balls were of different size? I'd say yes, because mass is not relevant in Coulomb's law.

hi there, just some questions to stimulate answers, looking for allll different types of responses, so- go ahead and answer! Does sin exist? What is your understanding of sin? Is sin the same as the concept of wrong? Where did your understanding of right and wrong come from? Are the seven...

the questioon is this: A balloon of radius 34.5 cm is sprayed with a metallic coating so that the surface is conducting. A charge of 1.05 × 10-08 C is placed on the surface. What is the potential on the balloon's surface? how i solved it: -apply the guass law, which gives me the Electrical...

Another view of the concept of "time." Dear Friends, I am new to these most interesting forums. I am very pleased to have discovered them. Perhaps I can add a subject that might also be of interest? Some philosophers, theologians and even some scientists seem to feel that "time"...

Hello all I was just wondering if an object is stationary, how can it still possesses kinetic energy? Is it due to the reference frame? Does everything possesses kinetic energy? Thanks

Alright, I absolutly do not understand this concept. I missed the lecture and the textbook does not seem to explain it very well. Here is a sample question: Two particles, each with mass m = 1.10 kg, are fastened to each other, and to a rotation axis at O, by two thin rods, each with...

I have always thought of the cocept of probability as a bit weird and thought I could post up a few questions to do with the basic concepts of probability and see how they can be mathematically proved. Here goes: 1) The method of measuring probabability we use, with 0< or = P < or = 1; is...

Consider two situations: 1) You are driving 50 mph and crash head on into an identical car also going 50 mph. 2) You are driving 50 mph and crash head on into a stationary brick wall. In neither case does your car bounce off the thing it hits, and the collision time is the same in...

A ball of mass m is being pushed off the top of a frionctless semi dome by a small negligible force. Find the angle where the ball left the surface. I know how to solve this problem, but I don't understand the concept behind it. Why does the normal force have to equal the centripeal force...

I had a conceptual question. Say I have a ball and I throw it against the wall and it bounces back. I have initial values for its velocity but not for the final velocity using the \vec{P}=m\vec{v} I noticed that momentum is not conserved. Well if momentum is not conserved then that means it is...

I have a question which puzzles me since the day my tutor pointed out to me. A uniform solid disk is set into rotation with an angular speed wi about an axis through its center. While still rotating at this speed, the disk is placed into contact with a horizontal surface and released as...

would someone explain to me the concept of space time? i know what it is but am having problems understanding it

We did a lab to illustrate this concept in class. The problem is I have no idea what this concept is trying to show. Basically the length of a string was altered from 30 cm to 80 cm. Then, at a 90 degree angle from the vertical of the pole housing the meter stick and the attached string, it was...

I'm a high school student and am a junior right now. I like physics, and quantum theory, perhaps because it will be our future. Therefore, in order to understand it, I need to know calculus. Since I don't have homework, I don't work out the problems. I try to understand the critical...

Im having trouble grapshing this concept. Can anyone please explain what voltage across two points means. Does it mean that one point is at a higher potential energy than the other point? Does it mean that the charges present are closer to the point a, and thus produce a stronger net force when...

I have one (hopefully) quick question for anyone out there willing to help. What's the difference between putting a pair of coordinate points, for example (3,4) in parentheses () and putting the between a bracket and a parenthesis like [3,4). Please respond soon because I need to know for...

lets say a structure has 3 resonance structures, i konw that the atoms don't move, but i read somewhere that the electrons do...hmmm and that the resonance hybrid is most stable ofthe resonance forms?? I am confused, what exactly is resonance? in actuallity, isn't there no resonance , just...

Which uses classic generators with a lot of friction. Also friction is the result of gravitation. An electronic engineer told me a classic generator uses about 30 to 35% of it's power to create the rotation against the electro-magnetic field. He told me that he never saw something similar to my...

here is the question: The density of gasoline is 730 kg/m^3 at 0 degree celsius. Its average coefficient of volume expansion is 9.6e-4. If 1.00 gallon of gasoline occupies .00380 m^3, how many extra kilograms of gasoline would you get if you bought 15.0 gal of gasoline at 0 degrees celsuis...

ok i got back my test today and its some basic stuff, but i don't get the difference between AVG speed and AVG velocity. One of my problems was 'The length of the barrel of a blowgun is 1.2 meters. Upon leaving the barrel, a dart has a speed of 14 m/s. Assmuing that the dart was uniformly...

hi, i'm reading brian greene's "the fabric of the cosmos" and in it he explains what a higgs field is. he says the potential energy of the field is shaped like a bowl with a raised peak at the center of the bowl. further he says the vertical height above the bottom of the bowl represents...

Recently, the Biology section of PF got a new thread, Cranial Size and Intelligence. One exchange in that thread concerned the 'intelligence' of species other than Homo sap. Clearly, not wearing a biologist's hat, each of us may be able to give a description of what we think the intelligence of...

Can someone put into plain english the following points: 1. What is the concept of Gauss' physical law. 2. Why is the rotation of an electric field zero. Cheers

What is "quasi particles"? Any ways to visualize this concept? I have so many troubles with this . Need your help, guys. :blush:

I think mass is attracted to the center of a 4th dimensional hypersphere (time neglected). Where there is a 4th spatial dimension. If by some craziness there was both an attraction betweent objects and the center of this 4D sphere, and objects to other objects(in the 4D) then you in theory could...