Conceptual Definition and 844 Threads

Say there's the following situation: A bullet with some velocity strikes a block connected to a spring. The bullet passes right through the block and the spring is compressed by x cm to the right of the block after the impact. Some internal energy is lost due to deformation of the block while...

Homework Statement A batter hits two identical baseballs with the same initial speed and from the same initial height but at different initial angles. Prove that both balls have the same speed at any height h if air resistance can be neglected. This was an example in the book and was "proven"...

A magnetic field points into the page. A conductive bar is moved to the right (perpendicular to the magnetic field). Why do the electrons move downwards toward the bottom of the bar? The book doesn't offer a good explanation of this... using right hand rule I would say that the electrons are...

Homework Statement A magnet is hung by a string and then placed near a wire as shown. When the switch is closed, the magnet rotates such that the ends of the magnet move as indicated by the arrows. At the instant the switch is closed determine: a) the direction of the current through the...

Homework Statement Given that a spring with a ball of mass m attached to it is oscillating in between x=A and x=-A where x=0 is the equilibrium position. Will the equilibrium position change when the the mass of the ball is doubled? 2. The attempt at a solution I think that the...

today in my physics course we were using jacobians to transform coordinate systems. This made me wonder if there was a way of deriving an optimal coordinate system to use for a given problem. -optimal meaning most simplified equation of a surface or bounds of a constraint (ex. cylindrical...

Homework Statement Pl2-4. The pilot tells you the wingspan of her plane and her constant airspeed. How would you determine the acceleration of the plane at the moment shown? Use numerical values and take any necessary measurements from the photo. Here is the photo to the problem...

Homework Statement After a long time after the switch is closed. 1) Rank the current of each component. 2) What is the voltage across each component? Homework Equations The Attempt at a Solution 1) The current across B is the same as the capacitor C because the capacitor is...

NEED CONCEPTUAL HELP ONLY! A package of eggs (mass 60.0 kg) sits on the flatbed of a pickup truck with an open tailgate. The coefficient of static friction between the package and the truck's flatbed is 0.350, and the coefficient of kinetic friction is 0.250. a) The truck accelerates...

Homework Statement I am in the midst of preparing for my midterm which is tomorrow, and I was going over a past midterm that has the solutions. However, there is one conceptual problem that I am not understanding, in fact, I think it is wrong... The diodes in a bridge rectifier have a...

Hey everyone, First of all, here is the applet so you can see what the problem looks like. http://session.masteringphysics.com/probhtml/applets/modatt2-14-4a.html I'm supposed to create an equation for acceleration; using m_1, m_2,Mu_k, and g. I'm not sure what the first step is...

Homework Statement At a certain distance from a point charge, the magnitude of the electric field is 500 V/m and the electric potential is -3.00 kV. (a) What is the distance to the charge? (b) What is the magnitude of the charge? Homework Equations The Attempt at a Solution a) 6 meters b)...

Homework Statement This isn't a homework question, but here goes: Suppose I have a system in an initial state |\Psi_{initial}> within the basis {|\Phi_{n}>} and later on I have a final state |\Psi_{final}> within the same basis, and I want to know the probability of ending up in the...

Homework Statement Hello all, If we have a bar that is perpendicular to a magnetic field, and that bar is being pushed to the left via an applied force, all the while a current (due to a voltage source and resistor) runs down through the wire. Therefore, there would be a total force comprised...

I have a very basic problem in understanding the relationship between electric field and displacement. If a field is applied to a dielectric, it is clear that this will cause the material to polarize, and one can define the permittivity of the material to quantify the size of this effect...

-The spring is stretched down and released with an initial velocity (v0) in the upward direction. The maximum velocity it reaches is v1. -The spring is stretched down and released with an initial velocity (v0) in the downward direction. The maximum velocity it reaches is v2. Rank the...

A long, thin metal (massless) bar is rotating in a circle at constant velocity, perpendicular to the axis of rotation. A weight is placed on the end of the bar such that there is no vertical movement of the weight or bar. What force counteracts the force of gravity on the weight?.

Homework Statement The hand in the figure is pushing on the back of block A. Blocks A and B, with mass B > mass A, are connected by a massless string and slide on a frictionless surface. Is the force of the string on B larger than, smaller than, or equal to the force of the hand on A...

I don't understand what I am doing wrong. Answer the following questions for a mass that is hanging on a spring and oscillating up and down with simple harmonic motion. Note: the oscillation is small enough that the spring stays stretched beyond its rest length the entire time. Answer...

My question is a little different in that I don't need help with the calculations for my problem, but rather I just need help understanding a concept. Take a look at the situation below: [PLAIN]http://img546.imageshack.us/img546/3459/phys.png The problem is then, "What is the maximum force F...

Homework Statement a disk is rolling on a flat horizontal surface.only rolling friction will act on the body.(true/false).ans false WHY?a body rolls.therefore sliding friction can't act on body.(true/false).ans. false WHY? Homework Equations The Attempt at a Solution since the...

Homework Statement Problem as written in text (Eisberg, 2nd): If a particle is not bound in a potential, its total energy is not quantized. Does this mean the potential has no effect on the bahavior of the particle? What effect would you expect it to have? Homework Equations The...

Homework Statement a) Does the initial speed of an object have anything to do with its acceleration? b) Does the direction of an object’s initial velocity have anything to do with its acceleration? Homework Equations N/A The Attempt at a Solution Does the initial speed of an...

Homework Statement A 3-lb horizontal force is applied to a 10-lb block on a rough horizontal surface. The block is initially at rest. If \mus is 0.5 and the \muk is 0.4, the frictional force on the block is? Homework Equations FN=mg Fk=\mukFN Fs,max=\musFN The Attempt at a...

Homework Statement A simple Atwood machine composed of a single pulley and two masses, m1 and m2 is on an elevator. When m1= 44.7kg and m2=45.3kg, it takes 5.00s for mass m2 to descend exactly one meter from rest relative to the elevator. What is the elevator's motion? (That is, is it moving...

Homework Statement When dealing with magnetic circuits, if the question explicitly states to ignore fringing, then the flux density of the gap will equal the flux density of the core, correct? In fact, if there are ever more materials, the flux density throughout the entire circuit (series)...

I am looking for books or papers that explain conceptual ideas that underlie the study of quantum fields. I am looking for something that clearly explains Field measurement. Most textbooks i am aware of emphasize on the development of formal techniques of Quantum field theory.

Homework Statement Find the stationary points of the function: z = ax^2 + by^2 + c For each of the following sub-cases, identify any maxima and minima. i) a > 0, b > 0 ii) a < 0, b < 0 iii) a and b of opposite signs.Homework Equations z = ax^2 + by^2 + cThe Attempt at a Solution Z'(x) = 2ax = 0...

In an isobaric expansion process, the pressure of the gas is kept constant. Because of the increase in volume the constant pressure can only be archived by increasing temperature. Then I want to ask is the pressure of the gas necessarily equal to the external pressure throughout the whole...

So as you all know, kinetic energy is.. K=\frac{1}{2}mv^2 The question I have is the followng. The "v" in this formula isn't really velocity, its speed is it not? Which is just the magnitude of the velocity vector with no direction information. Kinetic energy is a scalar quantity so with...

Just took my first E&M physics 2 test tonight, it was almost all conceptual. I feel like such a fool because it seemed basic yet most of the questions I felt uncomfortable with. My last physics class was more of the equation hunt type, working in symbols, see how things relate mathematically...

astronomy - conceptual, trigonometric parallax Homework Statement To determine a star's trigonometric parallax, we need at least 3 measurements of its position relative to much more distanct objects. Explain why this is true. (What else could change its position on the sky?) Homework...

(Is this thread in the right place?) A few questions on vectors: 1. I was wondering if anyone could explain in conceptual terms what the dot product and cross products represent. (I understand how these are calculated, but why are they important?) 2. Also, would it be accurate to describe a...

Homework Statement [PLAIN]http://img23.imageshack.us/img23/4554/physicshomework.png Homework Equations The Attempt at a Solution I have the right answer because it is obvious, but I wanted to practice working this out regardless, and I have something slightly different for...

The acceleration of an object can be non-zero when the speed of the object is constant. This is true. Why? If the velocity is constant, doesn't its derivative have a slope of 0?

Homework Statement How should the thrower adjust the angles of launch if he is throwing the object into a velocity of 40 m/s wind? Homework Equations N/A The Attempt at a Solution I really have no idea. Personally, I think throwing the object at a lower angle would help throwing...

Homework Statement A ^{238}_{92} U nucleus can catch a neutron with small kinetical energy. Then we'll get a ^{239}_{92} U nucleus. This nucleus has too many neutrons compared to the number of protons to be stable. How can the nucleus achieve a better balance between neutrons and protons...

I know that for electric field you always have to break E up into the x and y components for each charge---do you have to do the same thing when finding electric force using Coulombs law? I get the correct answer when i do NOT break F up into components (ie when finding F between 2 charges with...

My book says the following: NH4NO3 is weakly acidic as a salt because it is composed of the conjugates of the base NH3 and the strong acid HNO3. Why does that make it weakly acidic exactly?? Is it because the HNO3 is a strong acid, therefore it won't steal the protons that are...

Homework Statement An empty sled is sliding on frictionless ice when Susan drops vertically from a tree above onto the sled. When she lands, does the sled speed up, slow down, or keep the same speed? The sled slows down. Later, susan falls sideways off the sled. When she drops off, does...

Hello, Why does electromagnetic wave intensity attenuate exponentially with depth from its incident intensity in an object? Why is the relationship exponential? I just need a nudge in the right direction or more if you are willing. Thank you for any help!

If a sphere is moving through air. Will it have more drag if it is spinning while moving or just moving ?

Let's say I wanted to calculate the distance between the Earth and the Moon (assuming that the system in question only includes the Earth and Moon, the Earth remains stationary**, and the Moon undergoes a circular orbit around the Earth and thus acts as a satellite). The relevant equation is: r...

If you look at the diagram right below the headline "Electric potential diagrams" in http://www.physicsclassroom.com/Class/circuits/u9l1c.cfm" (about halfway down), you can see that in circuit A, the electric potential at point A is the same as that at point B, and likewise for points C and D...

Ah. I get it. Yes, well, it spread to PF, so... The standard definition of Conceptual Art back in the day was: art in which the concept of an artwork was, itself, the artwork. This was a subset of Modern Art, one weird branch of it. One of the best known conceptual artists was a...

In chapter 4 of A First Course in General Relativity, Bernard Schutz introduces the idea of a fluid element, a different one assigned to each point in a fluid. When he talks, in section 4.5, about the 3-volume of a fluid element, is this 3-volume defined with respect to the MCRF (Momentarily...

I was wondering about the first law of thermodynamics and isothemic expansion. Is there an increase in the the total internal energy of a gas through this process. If not is there a way to calculate heat (i can calculate work) through this process as both pressure and volume vary. Also is an...

Hi there. Here is the deal, today morning in my thermodynamic class we were making some exercises of stability, and then surged a question about internal energy. The thing is I thought that the internal energy should be always positive in sign. This doesn't mean that the variation must be...

Homework Statement A golf ball is hit so that it leaves the ground at 60° above the horizontal and feels no air resistance as it travels. Which of the following statements about the subsequent motion of this ball while it is in the air is true? a. Its acceleration is zero at its highest...

I have some concept problems that I cannot seem to master. I have them narrowed down to what I think the answers are but I keep getting them wrong. I'm supposed to choose all the statements that are false. A motorcycle moved along a straight road at a constant speed. The magnitude of its...