Conceptual Definition and 874 Threads

Homework Statement a block of mass m = 1.62kg slides down a frictionless incline.the block is raised a height h = 3.91m above the bottom of theloop. (a) what is the force of the inclined track on the block atthe bottom (point A)? (b) what is the force of the track on the block at pointB...

Hi guys, This is a basic circuit that you'd commonly see in a flash Camera. Hambley says (roughly paraphrased): When the electronic switch is toggled rapidly (1000s of times a second) the inductor charges due to a change in current. v=L(di/dt). The diode allows current to flow into the...

Homework Statement When we raise and lower indices of vectors and tensors (in representations of any groups) we always use tensors which are invariant under the corresponding transformations, e.g. we use the Minkoski metric in representations of the Lorentz group...

The question I'm wanting to ask is, Why does light travel through a vacuum? This is too big of a question to start with, though. Before making this thread, I read around and tried to make a starter question.If I'm not confused by the information I've found, a fundamental reason of why light can...

Homework Statement Q.1)A gas cylinder is lifted from the ground floor to the first floor.What is the amount of work done on the gas?What is the amount of work done by the gas?Is the internal energy of the gas increased? Q.2)When we place a gas cylinder on a car and the car moves,does the...

Hello, I have some trouble understanding an expression for the magnetic field energy .There are basically two different general expressions: a)\int(\int_0^B\vec{H}.\delta{\vec{B}}) d^3r b)\int(\int_0^A\vec{J}.\delta{\vec{A}}) d^3r. For linear medium a) becomes\frac{1}{2}\int\vec{H}.\vec{B}...

The book "Black Hole Wars" used the following to explain the concept of a difference in time near black holes. Step 1: Find a massive black hole, large enough so that tidal forces will be harmless to a human near the Schwarzschild radius. Step 2: Lower a person down via a cable. Result: The...

I know to find the angle between two vectors you would take the arccosine of the dot product of the two vectors divided by the magnitude of both vectors multiplied. I know the angle between two vectors is always less than or equal to 180 degrees. The angle can only be found when both vectors...

Homework Statement If you swing a ball in a vertical circle using a thin string, at the bottom of the circle the tension in the string must be greater than the ball's weight. True or false? Homework Equations F = mvv/r F = mg The Attempt at a Solution The correct answer, it says...

Hello everyone, Two blocks M and m (M is more massive) are sliding freely with the same initial speed across a floor with friction coefficient μk > 0, and they come to a stop. Initially there is a distance x between them. While they are sliding to a stop, A) The distance between...

Homework Statement "Based only on the desire to limit minority carriers, why would silicon be preferable to germanium as a fabric for doped semiconductors?" Homework Equations N/A The Attempt at a Solution Silicon has a band gap of approximately 1.1 eV while the band gap of...

Homework Statement https://www.dropbox.com/s/17hsoz0zdfoston/Screen%20shot%202013-05-10%20at%2012.37.44%20PM.png 1) A voltage is applied to a solenoid such that a current is flowing in the indicated direction. Inside the solenoid is a single wire loop that is oriented in the same...

Any Conceptual Underpinning for Partial Reflection of Light (QED)? I recently partially read Feynman's QED. At one point, he says "The situation today is, we haven't got a good model to explain partial reflection by two surfaces;..." (page 24--can visit Amazon "Look Inside" to read) My...

I am not sure if this belongs here (My first post), and please move it or delete if need be. I am only a high schooler, with basic algebra/precalc knowledge moving to Calc BC next year along with Physics C. I do not want any of the prep book mumbo jumbo. I just want a physics books that...

Bear with me, please. My knowledge of Gibbs, bond formation, entropy and enthalpy is weak, and I think they're needed to figure this out. Suppose I have "some" sulfuric acid and "some" salt, and I mix them. At least two reactions are possible: H2SO4 + NaCl -> Na2SO4 + HCl H2SO4 + NaCl ->...

Homework Statement Homework Equations The Attempt at a Solution My answer is a because for ball B it loses kinetic energy when it drops into the dip and comes back up. I'm having a hard time picturing ball b when it goes down the dip.. does it drop down and then jumps up...

Since its inception lies on the calculation of interest rates is it a, so to speak, 'Financial' number? Also why is our Mathematician so determined to use it so much on integrals related to probability distributions? Is it because it is integrated with less lengthy calculations usually? :)

1. The full problem statement, all variables and given/known data The problem can be found http://www.astro.umd.edu/~chris/Teaching/ASTR498E_Spring_2006/homework5.pdfif any of my description is lacking. I have solved successfully part a), most of b), and c) for the problem, but part d)...

1. Problem statement Immediately after being fired from a cannon, a high speed cannonball does not posses.. a) mass b) force c) momentum d) kinetic energy e) but, it has all these qualities while moving! 2. Related equations 3. Attempt at solution I'm thinking the cannon ball does not...

In short: Why are galaxies flat? In more detail: A very large mass M is at rest in vacuum, rotating at point O. Its axis of rotation is the xz-plane with angular momentum \vec{L} directed along the positive y-axis. What forces do the following masses experience? (Units of distance are...

1. Problem statement. A spring powered dart gun fires darts straight downward towards the Earth from the same height each time. First it fired a regular dart, then a dart with twice the mass. Which dart takes the least time to reach the ground after exiting the gun? A) the regular dart B) the...

L = r x p What's the significance of angular momentum, L, acting along the z axis? Angular momentum is being compared to translational momentum, p = mv, but translational momentum is acting the same direction of the velocity, right? Thanks for any help! edit: this is a nice gif...

Homework Statement An ice cube with many air bubbles is places in water, does the water level rise, sink, or stay the same when it melts? Does your answer change if the ice cube is filled with many grains of sand? Homework Equations The Attempt at a Solution I'm not too...

How are magnetars self-sustaining in light of the fact that they surpass the Eddington Limit? L_Eddington=4πcGMm/σ_T I read that that was a big reason the sources of the superstrong g-ray bursts were originally believed to be closer than magnetars actually are but I can't find why they...

Do any celestial bodies not have magnetic fields? Why? I'm having a difficult time finding good resources for dynamo theory a question about that... So first what I know: 1 - The Sun has a nonmetal hydrogen/helium plasma interior which is generating a magnetic field 2 - the Earth has a...

Hi there! I understand the tendency of physicists to stick to the math, and the logic itself, and to often avoid attempting to conceptualize a process or law, but that's kinda the opposite of what I'd like to do here. I don't mind at all if you refer to the theory, math or logic, and id...

Homework Statement A large barge filled with scrap iron is in a canal lock. If the iron is thrown overboard, does the water level at the side of the lock, rise, fall, or remain unchanged? Homework Equations None. I like math a lot but this class I'm taking is a prerequisite to...

I am a freshman in high school and I want to major in physics and probably mathematics in college. I would like to learn more physics and I think that math is a very important part in learning physics. However, I don't know algebra II, trigonometry, or calculus so I was wondering if I should...

1. Problem statement, all variables and given/known data. A sled weighs 2 Newtons. It is set in motion over a frictionless surface by a rocket motor with a weight of 1 Newton. After the fuel has been expended, the sled is coasting at a speed of 2m/s. How much horizontal force did the rocket...

http://i.imgur.com/ZCcaZpq.png I have the solution manual, so this is more just a question of why, rather than what. I understand that with the switch open: vA = 3v vB = vC = 0v i0 = 0.25 mA When the switch closes it creates a short that makes the two 6kΩ resistors irrelevant...

Homework Statement http://postimage.org/image/7rgmo1527/ How is the speed decreasing and acceleration decreasing in this problem? Homework Equations Kepler's Laws? The Attempt at a Solution I remember in lecture my professor was saying something along the lines of objects...

I'm having a lot of "simple" conceptual doubts when I try to study eletrodynamics in a qualitative way. Look at the circuit below http://img802.imageshack.us/img802/5349/suidbfhksdbgsdfg.png First we have a capacitor and a generator of voltage V (A). We wait until the capacitor is fully...

Homework Statement If I have a function that is not defined at a point in its domain is this the same as saying it is discontinuous? Homework Equations The Attempt at a Solution

Homework Statement Which of the following statements is/are true? Choose all that apply. a. The total mechanical energy of a system, at anyone instant, is either all kinetic or all potential energy. b. The total mechanical energy of a system is equally divided between kinetic and...

I'm just trying to get a conceptual grounding for the circuit problems in our book. So I understand that a circuit maintains a potential difference via redox reactions. The electrons have a desire to flow, so they do so. The potential difference and the conducting wire allow the...

Homework Statement Bronco Brown wants to put Ft =∆mv to the test and try bungee jumping. Bronco leaps from a high cliff and experiences free fall for 3 seconds. Then the bungee cord begins to stretch, reducing his speed to zero in 2 seconds. Fortunately, the cord stretches to its maximum...

Hi PF, What is the conceptual difference between potential barrier and potential difference? both have an electric field associated with it. so is potential barrier a sort of potential difference itself and will it cause current flow in a closed circuit like diode shorted. Also why cannot we...

For amperes law it is stated that: ∫Bdl=μIenc My confusion is that B is that for example here now on Earth if I have a compass. It interacts with a the magnetic field of the Earth and points north. There is no I-enclosed yet there is still a magnetic field? Also another Amperes Law...

Homework Statement This isn't an assigned problem, but it's the on conceptual question in the chapter that's bugging me, regarding the Compton effect. In the Compton Effect...(other questions)...The incoming photon's wavelength \lambda is assumed to be known. The unknowns after the collision...

Homework Statement https://aapt.org/physicsteam/2010/upload/2009_F-ma.pdf See # 14 Homework Equations None really, perhaps keep in mind that 1) p is conserved in the absence of external forces 2) L is conserved in the absence of external torque 3) Mech E is conserved if no energy is...

Homework Statement Let A be a 5x3 matrix. If b=a1+a2=a2+a3 then what can you conclude about the number of solutions of the linear system Ax=b? Explain I don't have the solution for this problem, and my first thinking was the system would be overdertermined, and be most likely...

I have always thought of G.P.E as how much a constrained body wants to fall in the direction of Gravitational Force Feild.But a while back i came across the concept of Gravitational Binding Energy. The book said that it was the Modulus of G.P.E and it was the energy by which an object is...

According to Carnot's theorem η≥η' where η corresponds to a reversible machine and η' is not necessarily reversible, so far so good, the problem is that it is ussually assumed that when η' is irreversible the inequality must hold however a could not find a rigorous demostration of this within...

Hey Folks, I am a third year electrical engineering student and just want to clarify a concept involving electromagnetics/transformers. When supplying magnetization current to a transformer (assume sinusoidal), this induces a time changing magnetic flux in the core. The time changing magnetic...

Hi all, I have a conceptual difficulty with the idea of induction of a current in a wire due to a changing magnetic field. Initially I was very comfortable with the idea. Upon seeing the typical setup of a square wire being rotated in a region of uniform magnetic field, I was happy to accept...

Books say that we have 46 (or 23 pairs) of different chromosomes in human which determines how we look like and our sex. I now have some conceptual questions about chromosomes 1. I know that chromosomes exists as pairs in body cells except sperm cell and egg cell, but is the chromosome...

I have some conceptual questions regarding capacitors and dipole antennas. Consider a parallel plate capacitor made with two conducting plates, initially uncharged. If I connect each plate to a different terminal of the battery, charge will start to flow from one plate to another. Consider...

Hello all, I had a question about Electromagnetic waves. Although it isn’t homework (just to settle something in my own mind) I thought this would be the best place to put it. Perhaps it would be best if I could explain a situation I could understand and then hopefully someone could bridge...

This is a conceptual question that has to do with SG devices: You're given amplitudes for an electron for Sz. What will happen if that same electron is passed through a Z-apparatus? And then one in the x-direction? From my understanding the electron then has equal probabilities of spin up...

Homework Statement A cone of height h and base radius R is free to rotate about a fixed vertical axis. It has a thin groove cut in the surface. The cone is set rotating freely with angular speed ω0 and a small block of mass m is released in the top of the frictionless groove and allowed to...