Constant Definition and 1000 Threads

With regard to Rutherford's atomic model, and Rydberg's discovery in general for the hydrogen distribution lines, what does Rydberg's constant physically mean? Its unit is m ^ -1, as if it were a rate, but it was not clear to me its physical meaning. And why does it grow with atomic mass...

I found this interesting thermodynamics problem on another site. I thought PF members might find it challenging to attack. I'm not asking for help since I've already solved it. So pease feel free to present your entire solution if you desire. Chet

g=9.81 m2g=m1a, a=(m2/m1)g=0.8g F=0.8g x (M+m1+m2)= 0.8g x (21+5+4)= 0.8g x 30= 235.44 N. The answer key however indicate that the answer is 392N. This made me think that the tilt of m2 has something to do with it, but I can't see how much it will make F larger than the above answer.

My book uses ##1/2m_1v_{1c}^2+1/2m_2v_{2c}^2=1/2m_1v_{1c}'^2+1/2m_2v_{2c}'^2## to show that the angles of deflection of the collision between two particles are the same in the centre of mass frame. However, I am doubtful that one can apply the conservation of energy to a "moving" system because...

Hi, First of all I hope it doesn't bother if I ask too much question.I found the values of ##u1,u2## for 2 differents posistions ##(r1,r2 )## and I now have to determine the spring constant (k).I'm thinking about using$$ F= -kx $$ with ##F = -\frac{du}{dr}## then $$ U = \int -kr \cdot dr...

Assume a solenoid coil(made up of ##N## windings) placed in the horizontal(##\hat{y}##) direction and in a constant uniform magnetic field. Would an induced current run through the(closed) coil if it spins around its central horizontal ##\hat{y}## axis? My guess is "no", since such a current is...

Show that for all real numbers $x,\,y,\,z$ such that $x+y+z=0$ and $xy+yz+zx=-3$, the expression $x^3y+y^3z+z^3x$ is a constant.

I can understand how it can be explained using the change of momentum to find the average force on the belt, then us $$P=Fv$$ to get the power. What I didn't understand is why the energy solution won't work. If in 1 second, sand with mass m has fallen on the belt and accelerated to speed v...

Left and right piston produce same vertical force.On both piston, side force is zero,how this is possible if left piston don't has simetrical shape? Why shape of object is irrelevant when fluid has constant/same pressure around object? How can I prove with integration of pressure over left...

Hello everyone. First my english is not good, sorry for that. So i am not a physician, i am just somebody who wants to learn things by myself, and therefore i don't have many people to ask from, if i am stuck. So here it goes. There are many threads about this question already, and i am still...

honestly just need some help here i understand the physics just not how to code it or the syntax of python

What I tried to do was using the fact that the wave function should be continuous. Asin(kb)=Be^{-\alpha b} The derivative also should be continuous: kAcos(kb)=-\alpha Be^{-\alpha b} And the probability to find the particle in total should be 1: \int_0^b A^2sin^2(kx) dx + \int_b^{\infty}...

Could someone please help me understand why ##h## isn't known as Wien's constant? In his "approximation": it just looks like he used the wrong distribution function (Maxwell-Boltzmann) with ##h\nu## correctly for energy And why is the correct distribution function $$ \frac 1 {e^{\frac E...

for example, I want to know velocity of a person when time is equal to t, that person start running from 0m/s (t=0s) to max velocity of 1m/s (t=1s). I am thinking that this is like rain droplet that affected by gravity and drag force, where force is directly proportional to its velocity, to make...

I am not getting any ideas to solve this without the universal constants. The method that I want to use invloves the speed of light, which is a universal constant.

Is the below Displacement time graph posible? if an object is in motion at a constant velocity, is it possible for it to stop instantaneously, or does there have to be a decelaration? According to Newton's first, an object will remain in its state of constant velocity unless acted upon by...

My questions is: Depending on which metric you choose "east coast" or "west coast", do you have to also mind the sign on the cosmological constant in the Einstein field equations? R_{\mu\nu} - \frac{1}{2} R g_{\mu\nu} \pm \Lambda g_{\mu\nu} = \frac{8\pi G}{c^4} T_{\mu\nu} For example, if you...

I’m obviously looking at this the wrong way but…..with reference to the formula e = mc2 isn’t “c” (the speed of light) a constant? So if that is true doesn’t c2 (or any other multiple of c) equal c?

https://www.physicsforums.com/threads/what-are-the-best-parameters-for-lcdm.831858/ Hello. In the above linked thread from 2015 Science Advisor Chalnoth replies to Earnest Guest. First, the cosmological constant has been a component of General Relativity pretty much from the start. The way...

In my book it has the following example, A particle confined to the surface of a sphere is in the state $$\Psi(\theta, \phi)= \Bigg\{^{N(\frac{\pi^2}{4}-\theta^2), \ 0 < \theta < \frac{\pi}{2}}_{0, \ \frac{\pi}{2} < \theta < \pi}$$ and they determined the normalization constant for ##N##...

Visualize the following scenario. A star such as the sun, and a planet such as Earth are located in a solar system. A photon travels from sun (x0) to Earth (x1), and a satellite is in the midway observing the photon. This is relates to Einstein's special relativity. I ask this since it take...

Now this is how I've tried to solve this $$ v_e = u0 \cdot ln \frac {M} {M- μ \cdot t} $$ After putting in the values I get this; $$ v_e = 200 * ln 0,36 $$ $$ v_e = 73,54 \frac m s $$ Now I'd say that this is the correct way to do it, but this part is confusing me "What is the speed of the...

In the ch1 if solid state physics Mermin & Ashcroft, in the hall effect section these paragraph are about cyclotron frequency, but what the two last terms want to say(the screen shot of the page is attached)? And I can't understand what happens to hall constant in high-field regime?

So, the only thing which came to my mind in order to solve this problem was actually to write down the equations using the discharge function, being given two instants and their corresponding charges... but doing so I'm unable to find anything. Ideally, I'd say I should find the time constant...

So I tried to solve this in two methods, but I keep getting different results, and I don't know why.

Hi, If we multiply $En=-\frac{2\pi^2me^4Z^2}{ n^2h^2} $by $\frac{1}{(4\pi\epsilon_0)^2},$ it is the formula of electron energy in nth Bohr’s orbit. Why we should multiply it by $\frac{1}{ (4\pi\epsilon_0)^2}$ a Coulomb's constant in electrostatic force? Where m=mass of electron, e= charge...

For an ionic lattice, the contribution to the electric potential energy from a single ion will be ##U_i = \sum_{j\neq i} U_{ij}##, which can be expressed as$$\begin{align*}U_i &= -6 \left( \frac{z_+ z_- e^2}{4\pi \varepsilon_0 r_0} \right) + 12 \left( \frac{z_+ z_- e^2}{4\pi \varepsilon_0...

The principal equilibrium in a solution of NaHCO3 is HCO3-(aq) + HCO3-(aq) <-> H2CO3(aq) + CO32-(aq) Calculate the value of the equilibrium constant for this reaction. My solution: This overall reaction is the same as the sum of the following reactions: HCO3-(aq) <-> H2CO3(aq) + OH-(aq)...

Multipart question: 1) How long would it take to travel to the moon from Earth at a constant 1 g acceleration? 2) How does fuel consumption work with constant 1 g acceleration or acceleration in general? I read that "it doesn't take a constant amount of energy to maintain a constant...

what means unit j.s in plank constant As Planck's constant is the smallest unit of energy so what this unit j.s

My first attempt was using the period equation of a spring system. I've changed it into k=((2π)^2*m)/T^2, then put Earth's mass into "m" (5.972*10^24), then put the time required for one revolution of Earth around the Sun, 365 days into seconds, 31536000 sec, to "T" So I got (2.371*10^11 kg/s^2)...

Say that we have an instance where something falls down from a certain height with constant acceleration g. We know that the average speed with regards to the time period is less than (u+v)/2 since we spend less time at the higher speeds. How do we actually calculate the average speed over a...

We need to find the normal modes of this system: Well, this system is a little easy to deal when we put it in a system and solve the system... That's not what i want to do, i want to try my direct matrix methods. We have springs with stiffness k1,k2,k3,k4 respectively, and block mass m1, m2...

I am still rather new to renormalising QFT, still using the cut-off scheme with counterterms, and have only looked at the ##\varphi^4## model to one loop order (in 4D). In that case, I can renormalise with a counterterm to the one-loop four-point 1PI diagram at a certain energy scale. I can...

Approaching for the first time to these "higher level" topics is mind-blowing, and indeed I cannot understand why is the speed of light a constant... why doesn't it vary relatively to the emitter state of motion? And isn't it affected by gravity(I know it is affected in the sense of a spacetime...

The question was: I will also include the solution: So, what is the justification of the first formula [ω=√(C/I)]? I know how to derive simple harmonic equations, this one as I guess is probably similar? But I cannot connect as to how C is used exactly. And the second formula [ω'=ωβ], I...

Basically I just want to work out a constant acceleration problem in relativity, of the same kind of introductory physics. Vo= 0.9999c Vf = 0 D= 50 Au Accel, Earth frame? Accel, Ship frame? Time of transit, Earth frame? Time of transit, ship frame? Motion is 1-D. All origins line up at the...

This is my scope of the question, i could think to solve it by two steps, but before, let's give name to the things. X is positive down direction. X = 0 at the initial position o the platform Mass of the falling block is m1 Mass of the platform, m2 Spring constant k Δx is the initial stretched...

Wikipedia defines the derivative of a scalar field, at a point, as the cotangent vector of the field at that point. In particular; The gradient is closely related to the derivative, but it is not itself a derivative: the value of the gradient at a point is a tangent vector – a vector at each...

Hi, what I've done so far is solving equation 2) for ##U##, and replacing what I get in equation 1). Then, ##c_V## is equal to the partial derivative of ##S## with respect to T times T, so I've done that. The derivative is ##CNR/T##, so ##c_V=CNR## but those aren't the correct units for ##c_V##.

History & evidence can be found in: https://onlinelibrary.wiley.com/doi/full/10.1002/andp.201900013 https://phys.org/news/2015-04-gravitational-constant-vary.html {unacceptable reference deleted} The experimental data strongly suggest are actual x,y,z,t variations in the measured value of G

There's a constant magnetic field B. If a particle is acted on by a force qv*B (* cross) only, and the initial velocity v0 is normal to B, is the motion certainly a circular one (for any m, q, v0)? mv''=qv*B If one solves this equation (vector), it doesn't seem obvious.

Let $a,\,b,\,c,\,d,\,e,\,f$ be real numbers such that the polynomial $P(x)=x^8-4x^7+7x^6+ax^5+bx^4+cx^3+dx^2+ex+f$ factorizes into eight linear factors $x-x_i$ with $x_i>0$ for $i=1,\,2,\,\cdots,\,8$. Determine all possible values of $f$.

If G really not a constant then what are the implications in science?

The solutions start from the fact that c_v= (dT/dV)_s = -[(du/dv)_T + P], however I cannot reason where did that come from. Any help will be appreciated.

Let: Smaller block = m1 = 1 kg Large block = m2 = 2 kg Coefficient of friction between the two blocks = μ1 = 0.2 Coefficient of friction between larger block and floor = μ2 = 0.3 Tension connecting two blocks through two pulleys = T Angle between tension and horizontal = θ = 37o Friction between...

If anybody has studied the book: A First course in String Theory - Barton Zweibach - 2nd edition This statement is present in 6th chapter of book on pg 110

So, when I try to solve for expansion work, I don't know nothing about Pext. I've seen multiple times that they just replace Pext with Pint but I don't really get why. I thought about a few situations and I'd like for you to correct me if I'm wrong. If the system in vaccum: the simplest one...

Completely new to this and wondered if someone can explain what the correct equation of motion is if x is extension, t is time and a,b are constants x = b log (at) x = a t exp(-b t) x = exp(-b t) sin(a t) x = a sin(t)/b

##x^2(3x^2+4x-12) +k=0## ##(3x^2+4x-12)= \frac{-k}{x^2}## or ##(4x^3-12x^2)=-k-3x^4## ##4(3x^2-x^3)=3x^4+k## ##4x^2(3-x)= 3x^4+k## or using turning points, let ##f(x)= 3x^4+4x^3-12x^2+k## it follows that, ##f'(x)=12x^3+12x^2-24x=0## ##12x(x^2+x-2)=0## ##12x(x-1)(x+2)=0## the turning points...