Concept Definition and 1000 Threads

What exactly do we mean by rest energy of a particle ? It is known that electron has rest energy of .511Mev but what is meant by this ? An electron is never at rest (except in its own frame of reference) then why it is said rest energy ?

Homework Statement If A is an invertible square matrix, then Ax = b is consistent for each b in R^n 2. The attempt at a solution If A multiplied by A inverse is identity, then it would always be consistent. So I thought , if A is just randomly multiplied by some x, then it will still...

Homework Statement If I had something like, et*u1(t), how would I convert it to F(s) Homework Equations ua(t)*f(t-a) = e-asF(s) The Attempt at a Solution From the general equation of transformation, I don't have f(t-a) and I don't think I can make one out of the exponential...

Hello, I'm kind a new to this forum. Been lurking here for a while and got some thought that I'd like to get some advice on. But since I'm new, I better present myself a bit. I'm a programmer since my youth (age 42 now), and never got a formal degree in anything. Nevertheless, I've always...

Homework Statement Two objects with unequal mass are released from rest from the same height. They slide without friction down a slope and then encounter a rough horizontal region. The coefficient of kinetic friction in the rough region is the same for both masses. The lighter mass will travel...

Can someone please explain to me the concept of vortex breakdown?

I am having trouble applying the concept of momentum conservation to this problem. The particular problem I am having is in figuring out if I did part (c) correctly. A look at Puck A: It is evident that total the momentum is conserved before the collision because the external forces acting...

I love Gizmag, and they've presented a challenge. (Actually, Honda presented it; Gizmag is passing it on.) The link shows a Honda concept bike that appears to have no tires, suspension, or drive train. I can think of a few ways that the suspension, steering, and power system might be done...

Homework Statement Two boxes full of books are in contact with each other on a smooth table. Box H has twice the mass of Box G. If you push on box G with a horizontal force F, then box H will expereince a net force of? Homework Equations F =ma The Attempt at a Solution answer from...

Need Help Understanding a concept on Buoyancy! Homework Statement I have a beaker on a scale. I suspend a block on a string and place it in the beaker. Will the scale reading be higher or lower than before? I need someone to explain the concept please Homework Equations The...

ok, So I am in an entry level physics class (electricity & magnetism) and I am having trouble grasping the idea of voltage/electric potential. Wikipedia describes it as "electric pressure" but that is still pretty foggy. My professor relies heavily on mathematical derivations and barely says a...

I am a seond year Quantum Chemistry student. I am having a hard time understanding these concepts. I was wondering I can get help in this concept. How can it be demonstrate mathematically in the Hamiltonian operator that the function φ(x) = A sin(2x) + B cos(2x) is an eigenfunction of...

i thought i understand it but i guess i don't... you can expand a function in cosine f.s., sine f.s. and complete f.s. on some [0..L]. i thought that the coefficients a_n and b_n for complete expansion would come from sines and cosines respectively, but i guess that wouldn't make sense...

Tough Concept Question! Homework Statement A rifle is used to shoot twice at a target using identical cartridges. The first time, it is aimed parallel to the ground and directly at the center of the bull's eye. The bullet strikes the target at a distance of HA below the center, however. The...

Measurement is probably the most important act when we attempt to understand our universe; without measurement we would have no information at all. The problem is including measurements in our theory leads to complications which our difficult to describe. I will outline a couple of the problems...

Does this jump honor the concept of physics?? http://www.youtube.com/watch?v=2YMQR13ia... -James Bond: Casino Royale Explain what is wrong with the action scene and how the segment should be modified so that it honors the laws of physics. The only thing I can think of is that the...

Situation 1 A box is suspended from the ceiling by two ropes each at an equal angle lesser than 30 degrees with the horizontal. Why is the tension of either rope greater than the weight of the box itself? Situation 2 A bungee jumper momentarily comes to rest at the bottom of...

For insulators the excess charge stays on the outside of the object. For conductors the excess charge travels through the sea of electrons until the net charge inside the object is zero with the rest of the charges pushed to the outer edges of the conductor. So with both the excess charges...

Homework Statement If you had a rectangular prism and split it in half, half iron, half wood, and let if float on water, would the buoyant force be different on the different sides? The Attempt at a Solution I originally thought since the iron was more dense than the wood, it would...

Why do we take ideal voltage source to have 0 impedance and ideal current source to have infinite impedance. Please explain mathematically also!

Consider a ladder leaning at a certain angle to the horizontal leaning against a wall on the point of slipping. Does the vertical component of force at the point of contact between the ladder and the floor equals to the weight of the ladder? If the answer is no, are there any other force(s)...

I have a few questions and verifying statements regarding the concept as well as practical building of Faraday Cages. 1. A Faraday cage's mesh must have a grid with a spacing less than that of the wavelength that is intended to be stopped. 2. Why is it that foil and mylar also work as...

Hi Folks I'm studying about redundancy concept in nuclear power plants. I want to find a list of all nuclear power plants in which the number of safety(eccs) trains are mentioned.

Homework Statement Is the sun's gravitational pull on the moon greater or less than the Earth's pull on the moon? Well, the sun doesn't steal our moon away, so the Earth must be pulling harder, right? Well, if you do that calculations you will find that it is not true! The sun pulls more...

Homework Statement List the conditions of "a" under which the system: x + ay - z = 1 -x + (a-2) y + z = -1 2x + 2y (a-2) z = 1 i) Has no solutions: ii) Has a unique solution: iii) Has infinite solutions. The attempt at a solution Well, I changed the matrix into reduced...

I have just started to study the concept of a renormalizable theory in Weinberg's field theory book. I am not sure if my understanding of the process is correct and would like some additional explanation or corrections; As far as I understand in any theory there will be unrenormalizable...

When a problem with a number of equations is given, asking to find its volume, a student has a choice between the cylindrical shell method and the cross-section method. However, regardless of what method is chosen, do both answers end up being EXACTLY the same?

Notes by ScienceWeek: In the late 19th century, what we now call "classical" physics incorporated the assumed existence of the "ether", a hypothetical medium believed to be necessary to support the propagation of electromagnetic radiation. The famous *Michelson-Morley experiment of 1887 was...

Hi all, I'm new to this website, really pleased to have found such a great website to satisfy my mathematical and scientific queries and doubts! anyway, I am currently revising for major tests.. and I can't understand/solve questions regarding Arithmetic/Geometric Progression (if you know what...

the problem is: a block that weighs W floats exactly with 1/2 of its volume below the waterline. What is the buoyant force? Answer is W, but why is it W? I thought that its 1/2 W because only 1/2 of the volume is below the waterline. if the buoyant force equals to the downward force...

Let's say, for ease of reference, an electron strikes a mercury atom with just enough energy such that this mercury atom is excited to another energy level. What would happen if a photon struck this atom with the same amount of energy? I remember encourtering a True/False problem like this in a...

Hello, I have a question about momentum that showed up in my physics textbook. It's a True/False question, and I have the answer, it's just that I'm not sure how it works. Could someone please explain this to me? Many thanks. |Glider 1|-----> <------|Glider 2|...

I have a few questions about electric potential and electric fields. If two points have the same electric potential, is it true that no work is required to move a test charge from one point to the other? Does that mean that no force is required as well? Also, How much work is required to...

Hi all, I'm kind of confused right now about some concepts. - Dipoles are essentially point charges of the same magnitude but different signs that are a certain distance away from each other, right? -In my textbook, they were calculating a charged particle that is on the dipole axis...

I am trying to prove that the Limit as p approaches infinity of {integral from 0 to 1[|f(t)|^p dt]}^(1/p) is in fact equal to the max of |f(x)| between [0,1]. Any suggestions I am sure I need to set the limit to less than or equal to and greater than or equal to the max but i don't quite...

Homework Statement 1. A converging lens is used to focus parallel beams of red light and then later used to focus parallel beams of green light. Which focal length is longer? Explain 2. A photographer moves closer to his subject & then refocuses the camera. Is the camera lens now closer...

Homework Statement Given the partial derivative df/dx= 3-3(x^2) what is d^2f/dydx? I'm not sure if the answer would be 0, since x is held constant, or if it would remain 3-3(x^2) (since df/dx is a function of x now?)

Homework Statement im supposed to draw the circuit for a simple house In a household electrical circuit, there's 3 wires, the live one, the nueteral one, and the grounding one. I'v drawn it out as if it were a DC circuit, then replaced the wires with appropriate live, and nueteral wires, but...

Radio Contolled Helicopters Concept! Hi guys does anybody know concepts behind the Fixed pitch Radio heli principle Thnx a lot in advance

Homework Statement It's not a typical question but is a challenging question from my sir, That's consider 2 cases: 1- A capacitor connected with a d.c power supply 2- A capacitor (originally charged) with two ends open. These two cases undergo two changes,1- increase in the plate-to-plate...

Homework Statement http://img231.imageshack.us/img231/5296/physicspd2.jpg Homework Equations none really. The Attempt at a Solution 1. I think that the two outside magnets would attach to the middle one and their eventual velocities and accelerations would equal 0 but that...

This may sound like a strange question... I was walking away from my physics class today and I wondered if resonant vibrations were the reason my shoelaces become untied. I noticed that when I walk faster, and produce what I believe are more forced oscillations, they become untied more...

Hey guys, I'm back, finished my term in physics with a 96% final grade, thanks to all you guys. So i thought id try you guys before i went to find a chemistry help forum. I get the Mole Concept, kinda, here's an example question (i got an answer, not sure if its right, we don't get a "back...

I have a question about the flying pig. A flying pig is just a toy pig with wings that is hung from the ceiling with a string. When you turn it on, it flies in a circle and shows concepts of conical pendulum. But it only flies in one direction. If you push the pigs in the opposite direction...

Could someone explain the concept of a battery I've looked it up in my textbook and wikipedia, but it doesn't really help Here is what I think I understand 1. Charges (electrons) are made in the cell by chemical reactions 2. They complete the circuit by leaving one of the terminals and...

Please give some feedback on my latest drawing concept of 'injecting air into a tank instead of compressing it'. Thanks. http://darinselby.1hwy.com/airgulper.html

Over time, I've realized there are certain limits to how far the human imagination can go. Even for simple things, it seems that we can not imagine much further than what experience allows...anyways: How does this light and time thing work? How is it that time slows down as we go faster?? It...

Homework Statement Explain why the potential energy between a positive charge and a negative charge is <0 Homework Equations The Attempt at a Solution I honestly don't know, I've tried reading the text about electric potential and I just can't find anything on the subject.

I am what is called an LA (Learning Assistant) for an introductory physics class and I'm a freshman. One problem in which I have in convincing the students is how forces are equal and opposite. For instance: A large truck breaks down out on the road and receives a push back into the town by a...

hi everyone, I am having a tough time convincing myself about the virtual short concept in opamps, As i understand from texts, on the application of a voltage on one of the input terminals of opamp, the voltage at the other input terminal is also forced to match the voltage on the first...