Constant Definition and 1000 Threads

A block with mass m =7.1 kg is hung from a vertical spring. When the mass hangs in equilibrium, the spring stretches x = 0.23 m. While at this equilibrium position, the mass is then given an initial push downward at v = 4.5 m/s. The block oscillates on the spring without friction. 1)What is the...

Can someone describe for me the dipole pattern that was detected related to the fine structure constant? This thread talks about that pattern some. What I am trying to understand is how that dipole is oriented relative to the observer on Earth? Are we talking about a toroidal shape with a...

Homework Statement The figure shows the displacement y versus time t of the point on a string at x = 0, as a wave passes through that point. The scale of the x axis is set by ys = 84.0 mm.The wave has form y(x, t) = ym sin (kx - ωt+φ). What is φ? (Caution: A calculator does not always give the...

Homework Statement I know that for constant volume ∂q=du and so du=Cv.dT However i don't understand how did we get to ∂q=du by neglecting the vdP term of enthalpy What I am trying to say is, is enthalpy this ∆U+P∂V+V∂P or this ∆U+P∂V? I don't understand since the definition of enthalpy is...

how is this true? I get that it's the rate of change of flux, and if you have a graph of flux linkage against time, the gradient with a constant gradient then emf is constant since it IS the gradient... But how? If the flux linkage is increasing, why doesn't the emf?

I am wondering if equation $$C_v=(\frac{∂U}{∂V})_T$$ applies only to ideal gases or applies generally for any other system? The second question I have is can we use the following relation: $$dU=nC_vdT$$ in processes that are non isochoric (that is for processes where volume is not constant)? I...

I came upon this page that provides the answer: http://farside.ph.utexas.edu/teaching/em/lectures/node125.html But I can't figure out what gamma(u) is. Could anyone help?

Why is speed of light constant in all frames of reference. I don't understand.

Homework Statement I am just looking through some old notes I have from for cosmology, and there's something cropped up that i can't seem to figure out: Say I have two (or more) values for H_o each with errors such as: H_{o_1}=70^{+a+b}_{-c-d} and H_{o_2}=69^{+e+f}_{-g-h} How would I go...

Homework Statement The Earth's radius is 6371 km. If the Earth's radius were to increase by 30 m (0.03 km), but no change in mass, by what percentage would the Earth's rotational period increase? (Model the Earth as a uniform sphere) Homework Equations ∑Torque = Iα v = rω a = rα KE = (1/2)Iω^2...

Homework Statement A volumetric charge density ##\rho = \frac{A}{r}## is distributed in the spheric region ##r_1 < r < r_2## (##A## is constant). A point charge ##q## is located in the center of the sphere (##r = 0##). What should be the value of ##A## so that the module of the electric field...

Is it proved experimentally that the Planck constant is invariant in the moving system? If that experiment exists, would you show me that in detail?

Hi. With regard to the Fine Structure Constant, I have been trying to figure out the practical applications of the formula in nature but have had difficulty trying to discern what the 137 denominator in the equation represents. ie, it is 1 137th of what? Or, 137 whats? Is there a practical...

hi, i'm totally confused right now. I'm playing around with a simple orbital model of the sun and the earth. since my rigid body solver doesn't like the huge masses of those bodies, i just normalized the masses to those of the sun. so i have m_sun = 1 and m_earth=3.0044e-6 as dimensionless...

Hi Community, I have this tutorial question. When I look at the first question (a) I think it is FALSE as the surface area would not increase at the same rate as the radius. For the second question I am not sure if I am interpreting it correctly. If $$r=\sqrt{\frac{Ct}{4\varPi}+2}$$ where...

Hi, I'm a beginner on hydraulics and have been reading up a lot of literature. But I'm not sure if my assumptions are accurate and I hope I can discuss with other forumers here! My apologies in advance if my questions seem silly! Background: My goal is to drive a hydraulic motor at constant...

Homework Statement The mass is able to move in any direction. All springs are preloaded (compressed) to half their allowable loading capacity. Springs are not properly connected to the mass or ground (they are mounted on a rod on which the mass is moving). Ignoring all friction and gravity...

I'm confused about situations involving rotating frames in which the angular momentum is conserved and the initial velocity does not change. I'll make an example. Take a rotating carousel (constant angular velocity) with no friction on it and a ball. At the initial time instant the ball has the...

In this http://web.stanford.edu/~oas/SI/SRGR/notes/SRGRLect6_2007.pdf, it is stated: Likewise, objects in spacetime all move at constant speed c in spacetime but if you change its direction, say by moving at speed v in the x direction, then spatial speed will change and so will the speed along...

"A 2.4% Determination of the Local Value of the Hubble Constant" by Riess et al has led to some excited news stories recently. I don't see it discussed anywhere here. Looking for the essence of the paper, I note three things: The two measurements considered are "the Hubble constant ... measured...

Homework Statement A car traveling at an unspecified constant speed passes a parked motorcycle cop. The motorcycle accelerated at an unspecified constant acceleration and reaches the car at unspecified distance d. At what point did the motorcycle's speed match that of the car, expressed as a...

How is pi/L part deduced in (n*pi*x)/L?

Hello all, I am in desperate need of some help. I'm writing my last paper for my senior capstone in physics (:smile::smile::smile:) and my experiment is Faraday Rotation. I CANNOT find a reference for the Verdet Constant of SF59 glass at 650nm (found V for many other wavelengths). I have...

Hey guys, This might sound like a simple question, but I'm just starting to look in depth into Einstein's theories. I'm confused on the question about a car driving at a constant speed o 65 mph northwards. If it changes it direction to drive northeast, it then loses some speed. How is this...

Already tried everything, mantissa, exponent, just do not know how to solve the problem, I would love to be able to understand it! 5 (1-e ^ -0.212765957) = e = 2.71 ^ = -0.212765957 here is my biggest question!

Just a quick question that I feel should be simple, but I'm unable to come up with a satisfactory answer. A constant signal has an arbitrarily small period (rather, it has no fundamental period), and so it seems to me that this means the frequency of a constant signal grows without bound...

Layman here, please excuse my ignorance. I believe to understand the basics of SR, GR, cosmic expansion, etc but questions come to mind now and then. As I understand, dark energy, the cosmological constant, vacuum energy, whatever you may call it, remains a constant per space volume unit. Empty...

A disclaimer: I'm trying to limit myself to asking questions on Physics Forums, partly because I feel I've gone way past my quota. Still, there is one question that simply won't go away, and it concerns the relative efficiencies between two forms of motion. The first involves continuous...

The Einstein gravitational constant (Κ) is usually written as; Κ = 8πG/c4 Can this constant be represented as wave-particle ratios of force? One ratio is a thermal ratio, it includes Plank temperature and Hawking temperature. The other ratio is a particle ratio including Plank mass. Can...

Homework Statement The 500-mg balance wheel of a certain clock is made up of a thin metal ring of radius 16 mm connected by spokes of negligible mass to a fine suspension fiber as in(Figure 1) . The back-and-forth twisting of the fiber causes the wheel to move in simple harmonic motion with...

Homework Statement We have a mass m at x = 0 attached to a spring with spring constant k which is moving at constant velocity v such that the position of the spring is described by X = l + vt where l is the equilibrium length of the spring. Solve for the motion of the mass. Homework...

H=p^2/2m+c What's c? It's of course a shift in energy, but can be thought also as a smoother and smoother real-space local potential that becomes a constant all over the space. On the other hand, why couldn't one think about it as a constant potential in reciprocal space? It's a shift in energy...

Homework Statement A yo-yo has a moment of inertia of 75.0 g-cm2 about its rotation axis. What is the constant torque required to make it spin to 300 rev/min in one second, starting from rest? Homework Equations ∑ = Iα The Attempt at a Solution I was thinking since the question is asking for...

Homework Statement A box is dragged a distance d across the floor by a force F which makes an angle theta with the horizontal. If the magnitude of the force is held constant but the angle theta is increased, does the work remain the same, increase, decrease, or first increase and then decrease...

Homework Statement [/B] Consider a barbell with two equal masses m that rotates around a vertical axis z not passing through its center with angular velocity \vec{\omega}. The barbell is forced to stay in this position by an appropriate support. Identify the forces exerting torques on the...

A slab made of unknown material is connected to a power supply as shown in the figure. There is a uniform magnetic field of 0.7 tesla pointing upward throughout this region (perpendicular to the horizontal slab). Two voltmeters are connected to the slab and read steady voltages as shown...

I 'd like to clarify some doubts about the rotational motion around a fixed axis of a rigid body, in the case the angular momentum vector \vec {L} is not parallel to the angular velocity \vec {\omega} . In particular, consider a horizontal barbell with two equal masses m , forced to rotate...

This Invited Review article just came out: http://arxiv.org/abs/1603.08658 The Atoms Of Space, Gravity and the Cosmological Constant T. Padmanabhan (Submitted on 29 Mar 2016) I describe an approach which connects classical gravity with the quantum microstructure of spacetime. The field equations...

Why does the free space permittivity has the value it has?

Homework Statement Ok so here is the prompt: a 3kg object is fastened to a light spring over a pulley. The pulley is frictionless and its inertia may be neglected. The object is released from rest when the spring is unstretched. If the object drops 0.1 meters before stopping, find the spring...

Homework Statement I am trying to use a slide wire potentiometer and a galvanometer to find the electromotive force of an unknown cell. I have heard that the balance point at which the galvanometer needle has zero deflection should be towards the centre of the slide wire as this reduces...

Homework Statement (Working with geometrised units) Consider the EFE ##G^{\alpha \beta }+\Lambda g^{\alpha \beta} = 8 \pi T^{\alpha \beta} ## work out (using weak-field considerations) an upper bound for the cosmological constant knowing that the radius of Pluto's orbit is 5.9 x 10^12 m...

Homework Statement You are asked to design spring bumpers for the walls of a parking garage. A freely rolling 1100 kg car moving at 0.66 m/s is to compress the spring no more than 9.0×10−2m before stopping. What should be the force constant of the spring? Assume that the spring has negligible...

In an electromagnetic wave like light,both wavelength and frequency changes but it's speed always remains constant.Why?

It states "a pure chemical compound is always made up of the same elements combined together in the same fixed ratio by mass." But how can a compound have the same elements ? For example,let's take ethanol,it is composed of hydrogen,carbon and oxygen.So three elements and not the same element.

I have an object that is decently thermally insulated. I want to plot how a constant cooling power of a few watts for a few minutes is going to affect the object's temperature. I need to account for how much heat is leaking in. Getting a constant cooling doesn't seem easy. If I instead use...

Homework Statement Given the following wave function valid over -a \le x \le a and which is 0 elsewhere, \psi(x) = 1/\sqrt{2a} Find the uncertainty in \left<\left(\Delta p\right)^2\right> momentum, and the uncertainty product \left<\left(\Delta x\right)^2\right>\left<\left(\Delta...

Consider a stable circular orbit (with a central force) subjected to small perturbations. The orbit equation is given by (3.45). The text argues that the ##\beta## in (3.46) must be a constant over the domain of ##r_0##: "Otherwise, since ##\beta## can take on only discrete rational values (for...

The triplet spin state with a normalisation constant of 1/√2 and the singlet spin state with the same normalisation constant... Where on Earth is this normalisation constant derived from? I've been scouring the Griffiths intro to quantum mechanics textbook and can't find info on it.

Many have claimed that if dark energy was not so small then the universe would fly apart and we wouldn't be here. However what if you increased the value of lambda and at the same increased the value of the gravitational constant ( or perhaps the amount of matter or dark matter in the universe)...