Conceptual Definition and 844 Threads

Homework Statement I can't find answers to following questions in the book Concepts of Physics by H. C. Verma.1. The apparent weight of an object increases in an elevator accelerating upward. A peanut seller sells his peanuts using a beam balance in an elevator. Will he gain more if elevator...

Homework Statement If equal masses of Xenon, Argon and Neon are placed in separate flasks of equal volume and same temperature, which one of the following statements is correct: a) The pressure of Neon flask is greatest. b) The pressure of Argon flask is greatest. c) The pressure of Xenon flask...

Homework Statement True or False: 1.Equipotential surfaces intersect: 2.Electric field lines are found within equipotential surfaces: Homework Equations E=Vd The Attempt at a Solution 1. I think this is false since the same reasoning describes why electric field lines don't intersect 2. I'm...

Suppose we are asked to find the time period of vertical oscillations of this system. Then should we find the component of displacement along each spring and then add the forces by vector method or should we simplify the diagram into series and parallel connection like in electrical circuits and...

Homework Statement Hi, I had a question regarding testing a regression models coefficients. Say there is a regression model that has the form: y = b0 + b1x1 + b2x2 + b3x3 + b4x4 + e For the sake of simplicity let: e be the random error, x1 is age, x2 is severity, and x3 is anxiety. y is...

A uniform beam of length L and mass m is inclined at an angle θ to the horizontal. Its upper end is connected to a wall by a rope, and its lower end rests on a rough, horizontal surface. The coefficient of static friction between the beam and surface is μs. Assume that the angle θ is such that...

Homework Statement -You are given a solution to Laplace's equation inside of a cylindrical region radius R. -Show that by redefining the radial variable r as R2/r you get a solution for outside of R. -Grounded conducting cylinder at r=R. Using a linear combination of the solutions in the...

Homework Statement You are at a stoplight when you see a car approaching from behind at constant velocity. To avoid getting rear-ended, you accelerate forward with constant acceleration. Assume that you have managed to start at the last possible instant to avoid getting hit, as determined by...

Homework Statement "Show that a solution of the homogeneous PDE ##au_x+bu_y+cu=0## cannot be zero at one, and only one point in the plane." My interpretation of this is that ##u(x,y)## is zero everywhere on the plane except on that point ##(x_0,y_0)##. Homework Equations ##w=bx-ay## ##z=y##...

One of the conditions to distinguish Simple Harmonic Motion from other harmonic motions is by the relation that a∝x where x is the displacement from the point that acceleration is directed towards But what confuses me is the constant of proportionality introduced to this relation: ω2 ω is...

Homework Statement Can we consider an inductor as a battery of emf ξ = -## L \frac {dI } { dt} ##? For the above circuit, ##V_A - V_B = V_C -V_D \\ -L \frac {dI } { dt} = IR ## Here, the inductor is acting as a battery of emf ## -L \frac {dI } { dt} ##. For the above circuit, ##V_A - V_B...

I have come up with a bit of a problem in my head regarding Newton's first law. If any of you could help me solve it that would be much appreciated. So if you throw a tennis ball (or any object really), and you throw it into an infinite expanse of nothing but void, it will travel forever, or...

A pendulum of mass m and length l is suspended from the ceiling of a trolley which has a constant acceleration a. Find the maximum deflection θ of the pendulum from the vertical. When I used work energy theorem, I got θ = 2 arctan(a/g). But when I took the equilibrium position and equated the...

My textbook states that an alternative definition of the change in potential energy is the work required of an external force to move an object without acceleration between two points. I am confused on why it says acceleration. Wouldn't that mean that the acceleration is 0 and therefore the...

Homework Statement Homework Equations[/B] I have a circuit that consists on 3 components in parallel: a current source Ia, a resistor R and a capacitor C. Ia is directed upwards, while the currents through the capacitor and the resistor are both directed downwards. Select the correct option in...

Can anyone please explain me the physical significance of these concepts?? Electric permittivity, Magnetic Permeability & suceptibility

So you have two alleles for every one gene, and the chromosome is composed of 2 homologous chromatids that have one of the 2 alleles for the specified gene on each chromatid. when you have to replicate that chromosome the way I understand DNA replication is is that you have a serious of...

I was unsure whether or not to post this question here or in the Nuclear physics sub-section, but it's a relatively simple question: Given that quantum tunneling exists, would it be possible to produce infinite energy via repeated nuclear fusion reactions? Now given the second law of...

It is not the laws of physics, but the forms of laws of physics which are the same in all inertial frames. Comment."The forms of laws of physics are the same in all inertial frames" is a necessary condition (put by scientists ) to get satisfied by something which has to be called as a law of...

Dear PFer's, I am looking for brief, conceptual books covering several physics fields. They should satisfy the following criteria: 1) brevity: optimal length between 100 and 200 pages 2) clarity: typically written by masters, go straight to the point and explain it very well 3) breadth: they...

Hello I would like to check my reasoning about solutions of first order PDE. I've spell out (almost) all details. I'll consider the following problem: find ##u=u(t,x)## s.t. : $$ \partial_t u(t,x) + a(x) \cdot \nabla u(x) =0 \qquad \qquad u(0,x) = u_0(x)$$ say with smooth coefficient and...

Homework Statement We start with a 2.50 μF capacitor connected to a power supply set to a voltage of 9.30 V. Then we increase the voltage on the power supply by 3.00 V. Now what is its capacitance? Homework Equations Q=ΔV*C The Attempt at a Solution The answer is 2.5 μF still, but WHY...

My question is conceptual but specific. I'm self-studying Townsend's text 'A Modern Approach to Quantum Mechanics.' In Sec. 2.2 pg 33 (in case you have the book handy), he introduces rotation operators, in the context of spin states for spin-1/2 particles. He states that the rotation operator...

Homework Statement Einstein developed much of his understanding of relativity through the use of gedanken, or thought, experiments. In a gedanken experiment, Einstein would imagine an experiment that could not be performed because of technological limitations, and so he would perform the...

Homework Statement Homework Equations The Attempt at a Solution I'm able to arrive at the correct solution here, but I'm fairly sure that my line of reasoning is not proper. 1. For the outermost shell, I discard the inner two shell/charge, since their effective charge is zero. Is this a...

First of all, I would like to admit that my understanding of general relativity is limited, though this will hopefully be remedied this summer when I take a GR class. I think we have all seen a sci-fi movie where the characters are stuck in a space where they are trapped in a sort of "warp...

Homework Statement A 1m^3 steel cube is to be floated on mercury (specific gravity=13.6). On each side of the cube there is a 5mm clearance. Assume that the container is open to atmospheric pressure at 100kPA. Find the mass of the mercury. Homework Equations P=F/A The Attempt at a Solution I...

Homework Statement Let two particles of equal mass m collide. Particle 1 has initial velocity v, directed to the right, and particle 2 is initially stationary. A: If the collision is elastic, what are the final velocities v_1 and v_2 of particles 1 and 2? B: Now assume that the mass of...

Homework Statement You are walking down a long hallway that has many light fixtures in the ceiling and a very shiny, newly waxed floor. In the floor, you see reflections of every light fixture. Now you put on sunglasses that are polarized. Some of the reflections of the light fixtures can not...

I'm having trouble understanding circuits, particularly voltage. So my question is more of a conceptual dilemma. Please correct my definitions and relations if it is incorrect. Voltage is the energy provided per charge, and this energy is converted to KE once the circuit is closed, or in other...

So in a graph where V is a function of x, when the slope is negative what does that mean about the direction of the field along the x axis? What about when the slope is positive?

I am learning about the polar coordinate system, and I have a few conceptual questions. I understand that in Cartesian coordinates there is exactly one set of coordinates for any given point. However, in polar coordinates there is an infinite number of coordinates for a given point. I see how...

I just did a problem for a final that required us to use a green's function to solve a diff eq. y'' +y/4 = sin(2x) I went through and solved it and got a really nasty looking thing, but I checked it in wolfram and it works out. Now, my question is this: After I got the solution from my greens...

Homework Statement For my high school physics class we made roller coasters out of card stock with various loops and funnels. We then had multiple questions to answer. I couldn't seem to figure this one out. Why does the power have to be found at the bottom of the loop? Explain in terms of...

Homework Statement It's not a homework exercise, it's more of a conceptual question to help my understanding of the subject. Imagine that you have a glass of height H filled with a fluid with density ro and viscosity eta. There is a hole somewhere on a side of the glass, at a height h relative...

Note: This is more of a math question than a physics question, but I'm posting it here since it's in the context of physics. I've been thinking about the classic example of a ball attached to a string and moving at constant speed in a circle. The acceleration is v^2/r and always facing in the...

Homework Statement Im having trouble knowing/remembering when my di and do should be positive or negative. Does anyone have any tips/advice for this?[/B]Homework Equations 1/f = 1/di + 1/do, hi/ho = di/do[/B]The Attempt at a Solution No solution. Just a question.[/B]

Hello, I've been thinking about the nature of Newton's Laws and had a question about two scenarios where I'm noticing a difference in the way the problem is framed and the outcome. I cannot sleep because it is wracking my mind. Let me start by stating what I know to be true going into the...

I question whether there would be a conceptual catch in EPR proposal to get both non commutative variables define with accuracy at one location simultaneously. The idea of separability that EPR introduced to questioning the completeness of QM is that whenever one measures a physical variable q...

I'm trying to get a handle on what magnetism really is. I know that charge in motion generates a magnetic field. I know that objects and particles can be permanent magnets when the magnetic fields of their elementary particles "line up." But how do stationary elementary particles have the own...

Homework Statement Two identical twins, A & B, are riding identical bikes up the same hill, both at constant speed. Twin A takes 20 seconds to climb the hill, while twin B takes 40 seconds. a) Neglecting all forms of friction, which twin consumes more energy? b) With friction, which twin...

Homework Statement A Person sitting firmly over a rotating stool has his arms stretched. If he fold his arms, his angular momentum about the axis of rotation : A.) Increases B.) Decreases C.) Remains Unchanged D.) doubles Homework Equations [/B]Conservation of Angular Momentum The...

Homework Statement Hey guys. I am attempting to do an end of the year physics project on gears on bikes and bike ratios. For the presentation I want to explain how gear ratios and the like work and demonstrate a homemade gear. I also need to have and experiment to go along with it. My basic...

How come the magnetic field outside a solenoid is practically zero? I've read reasons along the lines of: -The magnetic field cancels out on the outside. Of course the net force cancels out, but what if you have an object placed on just one spot? The force on that object clearly is not 0...

Homework Statement There are two forces on the 2.08 kg box. F1 is 20.5N. acceleration is happening in the third quadrant with a magnitude of 12.1m/s^2 and with an angle of 25.9 (in the third quadrant). Find the second force in vector notation. Homework Equations Fnet=ma The Attempt at a...

I find the common physics problem of accelerating boxes that are touching very confusing. (To be clear, boxes are on surface, force comes from one side and all boxes accelerate. Questions typically ask about magnitude of force between particular boxes). Once the boxes are accelerating, why is...

Homework Statement There is a simple set up with a cylindrical solenoid that is connected to a battery. Suppose the solenoid has a total resistance of 0.2 ohms. If the battery were attached to a regular resistor of R=0.2 ohms instead of a solenoid, the current in the circuit would...

Hello all! I am new to this forum, though I have been lurking for a long time. I intend to fill out my profile and introduce myself, but finals leave me with little time to spare at the moment. I have this final next week and would like to sort this out beforehand, hence the hasty post! Thank...

I don't think this question requires the template. Basically can some one simply explain something to me regarding asymptotes: The rules are that for horizontal the numerator has to have a higher power. For slant / oblique the numerator has to be just 1 higher than the denominator. How do you...

Homework Statement Consider a beam of unpolarised light incident onto air from a crown-glass with a refractive index of 1.52. Given that the incident light intensity has a power of 10mW, find the minimum incident angle when the power of the refracted light becomes zero. Homework Equations I...