Conceptual Definition and 844 Threads

This is more of a conceptual question. Homework Statement -------------------- 1.KE_{Max} = hf-\phi 2.\phi = Work Function. The minimum energy required to free an electron with a photon 3.E=hf This it the energy of a photon --------------------- In my book it says that" hf > \phi"...

I have been looking at a problem in magnetostatics about sheets of infinite surface current, positioned along the xy plane. Now clearly there is an Amperian loop parallel to the yz-plane. I understand why there would be no x component of the magnetic field, but I don't understand why there...

Homework Statement In using a ladder where the wall is smooth but the floor has a coefficient Us, why is it necessary to make the angle large? Homework Equations The Attempt at a Solution I'm a little confused by this, because I would think that you would want to make the angle...

Alright, I have a conceptual question regarding Green's Theorem that I'm hoping someone here can explain. We recently learned in my college class that, by Green's Theorem, if C is a positively-oriented, piecewise-smooth, simple closed curve in the plane and D is the region bounded by C, then the...

If you compress a gas in a piston(a monoatomic perfect gas for instance), what is the equation that gives you the temperature of the gas or amount of heat introduced in the gas vs the volume of the gas? And what is the ratio of energy that is transformed into heat vs into pressure? Is it...

Homework Statement In a performance test two cars take the same time to accelerate from rest up to the same speed. Car A has a mass of 1400 kg, and car B has a a mass of 1900 kg. During the rest, which car: a)Has the greatest change in momentum? b)Experiences the greatest impulse? c)Is...

Hi there, I've found some conceptual physics which i am confused about. Can anyone help me out? 1) Let's say if a particle is moving along an expanding spiral in a manner that the particle's normal acceleration[B] remains constant. How will the linear and angular velocities change in the...

Okay, so I've been trying to wrack my brain around this concept for a while but to no avail. PV = nRT (Preal + n2*V-2a)(Vreal - nb) = nRT From these equations, it's clear that real volume is greater than ideal volume under real conditions. I understand that this is because the molecules...

Homework Statement In a galvanic cell, the electrode that builds up a precipitate of metal (known as plating out) is: A. the cathode, and its surface is rich in positive charge. B. the anode, and its surface is rich in positive charge. C. the cathode, and its surface is rich in electrons. D...

Hi there everybody, while not a specific homework problem, in my PDE class i have come along a question which i don't quite understand. Now, when non-dimensionalising an equation, i believe the purpose is to remove the units from it? Now, we are talking about a biological population and are...

On p. 428 of Grinstead and Snell's Introduction to Probability, they say that fair* games with an infinite number of states (Markov states, if the game is a Markov process) need not remain fair if an unlimited number of plays is allowed. The example they give is two people, Peter and Paul...

Homework Statement I have a system with air flowing through a ducting with two inlets and one exit operating at steady state. There is no heat transfer or potential energy change. I know the mass flow rates and velocities at all inlets and exits. How would I go about finding the rate of change...

I just need an explanation: A spinning bicycle wheel is mounted on an axle you can hold in your hands. You hold it in front of you with the axle horizontal. The direction of the angular momentum vector is to your right. You then rotate the axle clockwise in a vertical plane as seen by you...

Is angular acceleration zero in this situation? A cylindrical space station located in distant space, rotates with constant angular velocity about its axis. An astronaut rotates with the station and is located at the perimeter, a distance R from the axis.

Homework Statement One likely theory for the origin of the Moon is that it was formed by the impact of a Mars-sized object on the young Earth. How fast would the object have to be going when it hit the Earth to vaporize enough rock to make the Moon? Homework Equations The Attempt...

Hey Guys, Say you have an air compressor with a constant volume. And were given the temperature and pressure at the inlet. And also, the temperature and pressure at the outlet. Would the mass of the air at the inlet equal the mass at the outlet? When applying the ideal gas law to the inlet...

Hi. I'm not sure if this is the right place to pose this question as it is not homework question. I'm studying RC circuits in second semester physics and I have a question about the electrons traveling through a circuit. Is it true that electrons won't travel down a branch of a circuit in...

Conceptual ---- Work Homework Statement In general, the work done by a force F_vec is written as W=\int_{\rm i}^{\rm f} \vec{F}(\vec{r})\cdot d\vec{r}. Now, consider whether the following statements are true or false: 1) The dot product assures that the integrand is always...

Homework Statement a. A fire engine is moving at 40 m/s and sounding its horns. A car in front of the fire engine is moving at 30 m/s, and a van in front of the car is stationary. Which observer hears the fire engine's horn at higher pitch, the driver of the car or the van? b. A bat flying...

Homework Statement There are two important conditions for a rigid body to be in equilibrium. The first condition is that the net force on a body must be zero. The second condition is that the net torque on a body must also be zero. 2,3. Relevant equations; attempt at solution. I...

Why conceptually, does the ground state for the particle in the box model correspond to n=1 while for the harmonic oscillator and the particle on a ring model it is n=0? For all three models, why don't we consider negative quantum numbers? attempt:...the particle in a box and particle on...

I read some books trying to understand the concepts of physics and here are the parts I got stuck at, if you could help me out, I would move on :) 1. Why can't momentum and position not be determined at the same time?(Heisenberg Uncertainity Principle) 2. How is 1 electron shot at a time...

Good afternoon, First of all, this is not a homework question, but I'm not sure whether it should be posted on the Homework section. My problem arose when I tried to think about what happens when a spring does work in two blocks. First, consider two blocks (1 and 2) on a frictionless...

Homework Statement This was a problem I needed help on. A train is traveling up a 3.73 degree incline at a speed of 3.25 m/s when the last car breaks free and begins to coast without friction. a). how long does it take for the last car to come to rest momentarily? b). how far did the...

This really isn't a homework problem with specific computations, rather it's a conceptual problem I'm struggling with; hence, the template doesn't really apply. (Please don't delete my thread!) In the derivation of the work-energy theorem W_C = \int_C \mathbf{F} \cdot d\mathbf{r} = T_2 - T_1...

If we have a resonator composed of 2 partially transmitting mirrors/grids and we excite the resonator from one end, say the left side then on the right we expect to get the characterstic transmission comb and on the left the inverse (1-Transmission) reflection curve. Whats giving me a...

Hi there, I've just joined the university for the 2nd week now. My lecturer has gave this homework which i have no idea to solve at all... It is not calculation but conceptual problems. Can anyone please guide me or help me with it? I'll truly appreciate and thanking you so much! Please help T_T

Homework Statement Ted is lying down and attempts to stand up. However Ted stands up too fast, and experiences dizziness. To compensate for this effect, the vessels in Ted's head expand. Why does this dizziness happen and why does the body respond by expanding the vessels in Ted's head...

Homework Statement A proton and an electron are each accelerated for the same distance across a region of constant electric field. Which experiences the larger acceleration? Homework Equations The Attempt at a Solution Would both feel the same acceleration but in the opposite...

1. Why is 2(pie)rh multiplied by the dr (change in r) equal to the change in volume? This is in the case of deriving the moment of inertia of a cylinder; the equation is (change in mass)=2(pie)(radius)(height)(change in radius)(density).Homework Equations The Attempt at a Solution I don't quite...

Homework Statement When a ball hits a wall and comes back, it originally had a momentum P. However, when the ball comes back, it has a momentum of -P (as in going in the opposite direction.) According to the law of conservation of momentum, since the ball had an impulse of -2P, the wall must...

Homework Statement A spring (in equilibrium) is attached to the top of a box that is moving at a constant speed vertically upward. However, if the box stops, does the spring go upward or downward? Homework Equations The Attempt at a Solution The spring goes downward because originally, the...

Homework Statement You are on a cart going at a constant velocity on a frictionless surface. You toss something off the cart in a direction that is perpendicular to your motion, thus lowering the mass of the cart/you system. Does the speed in the horizontal direction change? Person 1...

Okay I have several questions that have been bothering me for some time now, so bear with me please. How does integration work? Integrating the function f(x) between the bounds a,b finds the area under f(x) between a and b. But how does this work?If my function is f(x) = 2x and my bounds are...

Stars other than our sun normally appear featureless when viewed through telescopes. Yet astronomers can readily use the light from these stars to determine that they are rotating and even measure the speed of their surface. How do you think they can do this?

We have the index of refraction formula of n = \frac{c}{v} which essential states how much of a factor light travels faster in a vacuum than in this medium. Why don't they just have it as n=\frac{v}{c} so it states fractionally how much slower light travels in the medium than the speed of...

To be able to explain in a nutshell to my daughter why you can't go faster than the speed of light does this work: The universe exists now for us based on the expansion from a point. assume this expansion is occurring at a fixed rate. This runs the risk of assuming the answer I know. If...

Homework Statement A solenoid has 10 turns/cm and carries a 4-A current. A circular loop with 5 turns of area i cm^2 lies within the solenoid with its axis at 37 degrees to the axis of the solenoid. Find the magnitude of the average induced emf if the current increases by 25% in .1 seconds...

Homework Statement Curve on highway, 15 degrees, designed for 85 km/h and car goes 110 km/hr. Horizontal component of normal force on car is: a. in same direction as the centrifugal force b. parallel to the road and towards the inside of the curve c. in the same direction as the normal force...

In order for an object to be in static equilibrium a)the net force in all directions must be zero b)the net torque must be zero c) the object's velocity must be zero d) a and b are correct e) all of the above 2. I know that the net force in all directions must be equal to zero...

Homework Statement When two carts collide, is momentum conserved at each instant before, during and after the collision? If the carts are of equal mass what happens to their individual momenta during and after the collision?Homework Equations The Attempt at a Solution I'm actually unsure of...

Homework Statement Suppose you are in the back of a truck with a ball hanging by a string from the ceiling of the truck. If the truck is moving at a constant velocity on a smooth track, you will not know that you are moving. But if the truck is accelerating, you will see the ball and string...

Hello all, I have a quantum physics question which is more conceptual and mathematical than anything. Here's the question: Explain why ψ and its derivative have to be continuous and finite.

First off, this is not a request for a numerical answer. We've started discussing scattering matrices in my High frequency engineering class, and I'm having some trouble understanding wave mechanics. This got no attention in the homework forum, so I'll just copy paste from there. In a 2x2...

Homework Statement Suppose you are standing within the rim of a circular space station, in outer space. The rim revolves around the center of the space station at 290 m/s. If the radius of the station is 8784 meters, what will you weigh? (Hint: Find v^2/r and compare it to g.)Homework Equations...

Homework Statement It's not really a book problem, just a question I encountered in my reading. For a mass spectrometer, if r = mv / qb, then r is directly proportional to mass and inversely proportional to charge. However, my reading says that the higher the mass, the less deflection. I...

Ok so i understand that after a switch in a circuit is closed for awhile the inductor acts like a battery, however, what happens after the switch is opened after being closed for awhile. A review question asks whether the energy: - is converted to sound and spark - remains stored in the...

Homework Statement A = 2i + 3j E = 4i determine the integral of E dot dA Homework Equations Integral calculus, vectorsThe Attempt at a Solution I don't understand why one could do this. The integral is of E and dA, not E and A. How can I use A to determine dA? Do I take its derivative? Then I...

Homework Statement There is a box drawn on a horizontal surace. A force is being applied at an unkown angle in the positive x direction to the box. The angle is greater than 0 and less than 90. I'm assuming a standard coordinate system. "In the diagram above the box is stationary as the...

Hi In Halzen's "Quarks & Leptons" all discussed particle interactions conserve particle number in some sense (Actually particle number is not conserved but if you count the particles minus the antiparticles before the reaction you get the same "particles minus the antiparticles" number after...