Change Definition and 1000 Threads

This video shows how geologists figured out that a huge greenhouse effect nearly wiped out life on Earth 250 million years ago. The explanation is premised on an analysis of rock samples found at the Permian-Triassic Boundary in Utah. It involves a lot of Chemistry and Earth science so I...

I was trying to search but found no results. Is there a way to calculate how frequency will change if I stretch a string by certain amount (0.14 mm in my case)? I found out I can measure its frequency once stretched, but no results as of how to estimate new frequency ahead of the time. I know a...

The polarization referes to the direction of the electric field of a light wave which is to be one direction. The unpolarized light interacts with a material in various ways such as reflection, scattering, refraction. and each of which can transform an unpolarized light into a vertically or...

Hi everyone, The four fundamental forces are gravity (I understand that G.R. does not look upon gravity as a force but I'm not worried about that here), the Lorentz force, the weak force, and the strong force. I'm familiar with the inverse square law for gravitation and the Lorentz force...

This is supposed to be very basic, where the loop is held there is a declining magnetic field in direction (-z), therefore the current is supposed to be clockwise. However in the answers it is said the the current is anti clockwise. That doesn't make sense to me. Is there a mistake in the answers?

I understand that single integrals over a function can be interpreted as net change. Net change of the quantity between the bounds of the integration. But I am trying hard to understand if double integration can also be regarded as net change? That is, the net change in volume when the two input...

Having some trouble in answering this question What I have done so far is calculate the initial pressure difference, then used that to find the new pressure difference when pipe's A pressure increases by 34.4 kPa Not too sure of where to carry on from here? All I know is that if pipe A is...

Several maps, from ProPublica, showing how climate change may play out as changes in the US. Lessor amounts of similar data can be found in this PNAS publication. Some of the maps are interactive (different levels of continued emissions). The maps cover: temperature/humidity based most...

A cashier distributes change using the maximum number of five dollar bills, followed by one dollar bills. For example, 19 yields 3 fives and 4 ones. Write a single statement that assigns the number of 1 dollar bills to variable numOnes, given amountToChange. Hint: Use the % operator. #include...

I think I know what this problem means, but not sure how can I do quantitative work to solve it. I think only a would work because of friction of string, the reflected waves from the junction between two strings like that. Although, I am not sure how can I build the process, but this was my guess...

photos are in the speed of light which means that the fasts change in photons energy would take infinite time for the outside observer so does it means that the photons can't spin or interact with each other or have any kind of change

we know ##W_g = -\Delta U## but here to find ##\Delta U## we will need another equation won't it be wrong to write $$-\Delta U = -\int_1^{0.8}mgdy$$ as this equation is derived from ##W_g = -\Delta U## and as we have 2 unknowns we will need two equations. this is a rather easy problem but I am...

Question 1: Since Force=Change in momentum = ∆P / ∆t = mv / t Momentum of the water coming out=mv mv=ρVv=ρAv Force d/dt (ρAv2t)=ρAv^2 Force = 1000*40*30ms^2 Force = 3.6*10^7 N Question 2: This is where I am confused because I understand in an elastic collision total kinetic energy and...

I was content with the understanding of the Fourier transform (FT) as a change of basis, from the time to the frequency basis or vice versa, an approach that I have often seen reflected in texts. It makes sense, since it is the usual trick so often done in Physics: you have a problem that is...

Hello everyone! I'm new to the forum, and I've been trying to solve a problem that seems farily but I can't still convince myself of having the right (or wrong) answer. Imagine you warm up one mol of for example potassium hydride from standard temperature 298.15K to 673.15K (400 deg C). It is...

Let ##μ_k## = 0.5 ##F_a## = 10 Newtons ##\theta## is the angel of the Applied force. How will the acceleration of the block change if the angle of the applied force is increase by ##5^o##? Write Increase, Decrease or Stay the same. Recently we were discussing a question similar to this in...

I'm reading 'Core Principles of Special and General Relativity' by Luscombe - the part on parallel transport. I guess ##U^{\beta}## and ##v## are vector fields instead of vectors as claimed in the quote. Till here I can understand, but then it's written: I want to clarify my understanding of...

Algebra in this answer does not seem to flow right. Firstly, the 16, secondly the n term. Can someone explain or show me the right answer?

Can anyone explain the above answer to me? What does the "change in area" mean?

Since the Earth orbits around the sun and very slightly changes its relative angle and position, does the brightness of a particular star change from season to the season?

I am at a huge crossroads in life and in need of some guidance. I graduated two years ago with a B.S. in Physics from an R1 university, and am currently in my second year of a physics PhD program at a different R1 university. From the moment I had my first research experience in high school, I...

Because, ##F=ma=kv##, therefore, ##a=kv/m##. Clearly, the net acceleration ##A=-(g+a)##. Also, ##A=dv/dt=-(g+ \frac {kv} m )##, so cross multiplying and integrating LHS with respect to ##v## and RHS with respect to ##t## gives me: $$ v= e^{ \frac {-tk} m } * (u + \frac {gm} k) - \frac {gm} k $$...

I'm guessing that there must be some nuance that I do not quite understand in the difference between ##|p\rangle## and ##|E\rangle##? Like, later in the book even ##dk## is used as a variable of integration, where ##k = p/\hbar.## Surely this has effects on the value of the integral - wouldn't...

Isn't it $$\color{red}x\color{black}y$$

The second question is where I'm lost. The answer to the first question is 5.39 grams. The second is 10.3 grams. Until I saw the answer I was setting the equation up as if some of the original steam had condensed. But it appears that some of the original water changed into steam. Is it necessary...

So I have a cube in 3d space and this cube is made out of 8 coordinate points at each corner. Now I have a temperature reading at each point of these corner points. Inside the box I have another point, I want to be able to use the information from the 8 points surrounding the the one middle...

So we have ##x=\beta(1/2 mv^2-\mu)##, i.e ##\sqrt{2(x/\beta+\mu)/m}=v##. ##dv= \sqrt{2/m}dx/\sqrt{2(x/\beta+\mu)/m}##. So should I get in the second integral ##(x+\beta \mu)^{1/2}##, since we have: $$v^2 dv = (2(x/\beta+\mu)/m)\sqrt{2/m} dx/\sqrt{2(x/\beta+\mu)/m}$$ So shouldn't it be a power...

[Ref. 'Core Concepts in Special and General Relativity' by Luscombe] Let ##M,M'## be manifolds and ##\psi:M\to M'## a diffeomorphism. Even if ##\psi## weren't a diffeomorphism, and instead just a smooth map, the coordinates of the pushback of ##\mathbf{t}\in T_p(M)##, would be related to the...

I have been working with some time series data of spectral signals, each wavelength has a different signal, so I normalize the data so I can plot it effectively. However, I am struggling to quantify the new normalized data. I will give an example below. Normalizing data often refers to...

I'm studying 'Core Principles of Special and General Relativity' by Luscombe - the chapter on tensors. Quoting: The book goes on to talk about a switch to the spherical coordinate system, in which ##\mathbf{r}## is specified as: $$\mathbf{r}=r\sin\theta\cos\phi\ \mathbf{\hat...

(Sorry for the really basic question. Been 20 years since high school physics and I've been working in a different industry)

Definition of conservative field I use:-it is a field in which potential energy of system is independent of path taken. I understand that it is independent because whenever we take some path than all the perpendicular displacements with respect to force are not counted and if we go further than...

Hi everyone, I hope I can articulate what I'm thinking, as I'm unsure if this is specifically an "engineering job" problem or a job in general problem. I graduated with a BSEE, got an MS right after, and have worked in two companies so far. I had a pretty good gpa for both, over 3.6, so I...

Given the support [a, b] of a probability density function. How can I change the formula for the probability density function with a support [u, v]? Example: Given the beta distribution with support [a=0,b=1]: $$\frac{x^{p-1} (1-x)^{q-1}}{Beta(p,q)}$$ Then the beta distribution with support...

For an ideal battery (r = 0 Ω), closing the switch in (Figure 1)does not affect the brightness of bulb A. In practice, bulb A dims just a little when the switch closes. To see why, assume that the 1.50 V battery has an internal resistance r = 0.30 Ω and that the resistance of a glowing bulb is R...

(.174A-.181A)/.181A=-3.86% but it says it wrong, and I did (.181A-.174A)/.174A =4.02% but this was wrong too. I've tried 3.87%,3.86%,-3.87%,-3.67%,4.02%, and -4.02% but all were wrong. I'm really not sure what to do here.

In physics we often come across $$\rho=\dfrac{dq}{dV}$$ Does it mean: ##(i)## ##\displaystyle \lim_{\Delta V \to 0} \dfrac{\Delta q}{\Delta V}## OR ##(ii)## ##\dfrac{\partial}{\partial z} \left( \dfrac{\partial}{\partial y} \left( \dfrac{\partial q}{\partial x} \right) \right)## What does...

Hello everyone, I have a problem where I have to find the final displacement and final velocity which I have found however, I want to post few variations for that same problem which I am curious. It is more for my own knowledge > I would appreciate any help Please follow graph below with...

Will the available Volume of oxygen gas for use of patients increase when the pressure decreases from 12.4 MPa to 500 KPa? Is using boyle's law the right way to calculate the available volume?

Hi PF! I'm trying to edit two lines from files in different directories, U and controlDict. I want to change the lines with numbers from two other .dat files, VEL.dat (vector of numbers) and VEL_t.dat (single scalar number). Below is my attempt, but I know at least two things that are wrong...

Hello- In the attached screenshot from my textbook, I am trying to understand how they get from equation 6.5 to 6.5a. I have attached my attempt to solve it, but I am stuck evaluating the left side. I do not see how to get their result. Relevant information: k, T_w, T_inf, h and L are all...

In the Standard model the decay width for Higgs into fermion-antifermion pairs is $$ \Gamma_{fi}=\frac{\mathrm{N}_{C}}{8\pi}\frac{m_{f}^{2}}{\nu^{2}}m_{\mathcal{H}}\left [ 1-\frac{4m_{f}^{2}}{m_{\mathcal{H}}^{2}} \right ]^{3/2}$$ where the vertex of interaction between the Higgs and the...

Ok Just have trouble getting this without a function..

h and s can be obtained from "Saturated refrigerant-134a—Pressure table" however, how to get h2? it is not on the curve, and neither p or dV is given in the question. Thank you

Hi there ... How do I calculate the change of angular velocity, when demonstrating conservation of angular momentum? I mean the change of angular velocity depends on the ratio between the two (rotating) masses that moves a distance along radius, and the (rotating) mass of the system itself. In...

the entropy change for a reversible adiabatic process is zero as it remains constant. Is this a reversible process? assuming T1>T2: hot (h) water has mass M, temp T1 cold (c) water has mass nM, temp T2 let the final temperature be Tf if δQ=0 as the process is adiabatic, |Qh|=|Qc| so Qh=-Qc...

I have been amateur reading about beta decay. The example given for electron capture was krypton-81 into bromine-81. Going from a noble gas to a halogen gives rise to a big change in chemical potential energy. How is this energy accounted for in the equations of the reactant particles and...

Hi, just reviewing some thermodynamics from the textbook by Sears and Salinger, having a hard time conceptualizing this one. It's an isothermal change in pressure, so the volumes of the mercury and the air both change to reach equilibrium, but if it's a "good vacuum pump", then won't the right...

If thermal motion (collision of atoms) changes the direction of an atom, will that change the direction of spin? If so, how much time does it take from the change in the atom orientation to the change in the spin?