Work Definition and 999 Threads

If we look at system at constant temperature and volume which is galvanic cell, first law of thermodynamics states: $$ dU = dQ + dW' $$ Where W' is electrical work done by galvanic cell and Q is heat exchanged with surroundings. As far as I know electrical work is work done by electric field...

When we talk about systems at constant temperature and pressure, maximum amount of non-PV work can be extracted if process is carried reversibly and in that case it is equal to change in Gibbs energy of the system (decrease in Gibbs energy if system does non - PV work, A.K.A work is extracted...

Good day. I am studying Open Modelica and building RLC. I was given the following task: From the initial network make one (sample graphics on Scilab but needs in Open Modelica) As you can see in the graph that is presented in scilab, the graphs start from different points. Here is a list of...

From what I understand, the anomalous Doppler effect can occur when a charged particle moves through a medium faster than light would move through that medium; however in the paper, The Doppler Effect in a Warm Uniaxial Plasma, it mentions that this effect can occur when a dipole moves faster...

Hi, guys! Could anyone provide an explanation about how the following AM transmitter works? It is similar to the AM transmitter for project 122 of the Snap Circuit kit by Elenco. Does it work as a switching modulator?

Guys, I have a problem that really needs you guys to help, I know it is a stupid question but please bear with me: Context: You have a block on a slope(has friction) you use a string to pull the block up with constant speed. Problem: So according to the network theorem, the work net is equal...

-

As stated, part (a) says that the work done by the gravitational force ##\vec{F_g}## is 59 kJ. If ##W_T## is the work done by the elevator cable during the 12 m fall, then using the work-kinetic energy theorem, \begin{align*} K_f -K_i &= W_g + W_T\\ \frac12m({v_f}^2 - {v_i}^2) &= 59000 + W_T\\...

First i calculate n: 500000 g / 32 g/mol = 15625 mol Then I calculate V1: (100000 Pa * V1)/288.15 K = 15625 mol * 8.31 J/mol.k so V1 = 374.145 m^3 I calculate V2: 100000¨ Pa * (374.145 m^3)^1.3 = 300000 Pa * (V2)^1.3 So V2 = 160.703 m^3 W = ((100000 Pa * 374.145 m^3)-(300000 Pa * 160.703...

hi guys my analytical mechanics professor asked a question the other day about, how come the generalized forces##Q_{\alpha}## doesn't need to have a dimension of force, and the generalized coordinated ##q_{\alpha}##as well doesn't need to have a dimension of length, but the generalized work...

a)What is the total energy in the system? Only energy acting on the system assuming the track is level and there is no potential energy of the carts, is the potential energy of the spring. Comes out to 7.8125 using the potential energy of a spring equation. b) What are their velocities if the...

I took a stab at the question, but I don't think I did it right. I know that Work = Change in Energy thus, Work = final energy - initial energy Because there is no energy at the final position, then final energy = 0 (I'm not sure if this is correct). So I got the equation W = 0 - (1/2kA^2 +...

In the solving portion of the textbook, the reasoning of the author in solving this problem is that the net work done on the system is zero because the net force of the system is zero. So my question is how was the system in equilibrium (net force=0)? My thinking is that since it is stated...

Well, internal energy is the sum of the kinetic and potential energies of all the molecules within a given mass of a substance; this energy is associated with the random, disordered motion of the molecules. An example of internal energy is compressed gases; since gases occupy the total volume...

The Onion tackles black holes. https://www.theonion.com/step-by-step-how-do-black-holes-work-1846628568

APRIL 2, 2021 https://www.hawaiibusiness.com/videos/2021-best-places-to-work-online-reveal/ I was born in Hawaii! :smile:

Hello all, I am looking for some career advice. My current situation is that I am graduating with my bachelors in physics and chemistry in December of this year. My goal is to get a masters degree in a field that would enable me to work as an engineer at one of the aerospace/defense contractors...

if the Work done by friction is -4.73 for object #1 but the work done by friction for object #2 is -4.63, in which scenario is the Work greater - the signs are throwing me off. Also, let's say the initial elastic energy of a ball is 5 and its final energy is 0.27 (scenario #1) vs its final...

In my studies trying to get the Ricci tensor of 2° order i stuck in this expression: ##h_{\mu}^{\ \sigma},_{\lambda}h_{\sigma}^{\ \lambda},_{\nu}=h_{\mu \lambda},^{\sigma}h_{\sigma}^{\ \lambda},_{\nu}## So, to complete my calculations those quantities should be the same, but i don't understand...

For many of the problems in my engineering courses (as well as other STEM courses and maybe even in industry), much of the work is in algebraic manipulation of equations. These problems could be solved using by using symbolic expressions in a coding language like MATLAB. However, it is very...

W=-qEd =-(1.6*10^-19)(23)(0.75) = -2.76*10^-18 J However, the answer is 2.76*10^-18 J. Why is the word done positive and not negative? Since it's traveling in the same direction as the electric field, shouldn't it be negative work?

If evaporative cooling (Such as sweating) is due to the escape of the hottest molecules into the air thereby lowering the total average temperature of the water then that means that that hot water molecule has gone into the air and has made the air hotter, so then how does evaporative cooling...

Are you saying there are circumstances in which the work done in a magnetic field depends on the path taken?

I am a bit confused. My teacher solved this problem and his answer for the thermal energy produced was -147,000J. My book says it is 147000J. My teacher used the equation K2+P2=K1+P1+Wnc and my book used K1+P1=K2+P2+Wnc. Which one is it?

So I basically took the integral and ended up with W=PVf-A(Vf^3)/3-PVi+A(Vf^3)/3 so 65.7=72*5.3-A(5.3)^3/3-72(2.4)+A(2.4)^3/3 But when I solve for A I get the wrong answer of 3.179 when the answer is suppose to be 5.05. I've checked my calculation with an algebra calculator too...

Some RF transistors are not 'characterised' for lower frequencies, can they still be used? I get that a lower operating frequency (HF/1.8MHz) may not be the commercial target for an UHF transistor (>136MHz) so no effort spent on characterising them. Likewise HF transistors >1.8MHz not...

height to point A is 65m. no friction. comes to rest at point A. total mass of the roller coaster is 650 kg. the work-energy theorem states that the net work done on an object is equal to the change in kinetic energy of the object. kinetic energy is E=1/2mv^2. initial velocity is...

So I've just learned Norton's Theorem and I have this problem on my homework assignment that is wrong. I've checked the answer with a circuit simulator(PSPICE) and the simulation said that V0 should be a drop of 2V. However, my simplified circuit shows a voltage drop of 4V. I have been staring...

so the result I got is the energy lost by the field right??

We have a new boat, and it has surface piercing propellers. Half of the prop is above (out of) the water, and half is below. I can't quite understand how that actually works or why it would be better.

Specifically for part (i) and (ii), I get the rough idea that when the voltage of the AC source is decreasing, the capacitor can discharge to "cushion" the drop in voltage. However, I have some questions about when this occurs. 1. There is an assumption that the capacitor will be charged to...

Author's solution seems to assume that "carry 100 people/min" means "takes 100 people up the whole length / min", ie 13.3m/min=0.222m/s. But its lengthwise speed is actually 0.620m/s. In particular, why is my solution wrong (according to author's solution)? : I said since 100 people/min then...

The answers for author's solution differ slightly from mine when I convert his answers to SI. I think this is only a conversion issue as the differences are small but I wanted to confirm if my solution is correct: d=rt (distance = rate x time) so (12...

I know how to solve this using work energy theorem but how can one solve it starting from the fact that net force is centripetal? My attempt was "this means we only need an "anticentripetal" force of same magnitude, but centripetal force does 0 work hence new force also 0 work to counter it"...

Juri is tugging her wagon behind her on the way to... wherever her wagon needs to go. The wagon repair shop. She has a trek ahead of her--five kilometers--and she's pulling with a force of 200 Newtons. If she's pulling at an angle of 35 degrees to the horizontal, what work will be exerted on the...

I recently saw a video online of a white blood cell taking out a bacterium. This engaged my curiosity and I wanted to know why the WBC and bacterium behave the way they do. I learned about chemotaxis, but none of the explanations I have found satisfy my curiosity. What exactly is happening...

Suppose that we have two atoms with one proton one electron each, and these electrons interact with each other. The states for the electrons are the singlet(S=0) and the triplet states(S=1). My question is if i have to keep the nuclear spin of the protons parallel when i write the states, for...

The force on a charged particle that is moving through a magnetic field is explained in introductory physics textbooks. The magnetic field cannot change the kinetic energy of the charged particle because the force from the magnetic field is always perpendicular to the velocity, so no work is...

Here it writes Wby spring= Uinitial - Ufinal. So is it equal to opposite of the change in potential energy ?

Is my solution correct? $$ F(t) = at + b $$$$W=\int_t F(t)dr, ~~~~~~~~~ ~~dr = v(t)dt$$$$W=\int_t F(t)\cdot v(t) dt$$ $$ f = \frac{dp}{dt}$$ therefore $$v(t) = \frac{1}{m}(at^2/2+bt)$$then $$W = \int_t \frac{at+b}{m}\cdot\left(\frac{at^2}{2}+bt\right)dt$$ $$W = \frac{1}{m}\int_t...

Hello guys, I confess that I absolutely suck at math. Unfortunately my boss handed me what is basically a math problem I got to solve, and I have no idea how to do it cause of lack of my math skills. I am hoping someone can help me with this or I'm screwed. Co basically I've got this table in...

Hello! I am trying to do some molecular physics calculations, involving the calculation of the expectation value of certain vector operators (such as the electric dipole moment of the molecule) in given molecular states. In most cases assuming the Born-Oppenheimer (or adiabatic) approximation...

A force of 1 Newton times 3 meters, can that mean : a 1 kg mass pushed over 3 meters went from 0 to 1 m /s/s ?

I am curious about how mixing paints works. If I mix an ideal paint A and an ideal paint B what is the product mixture C? Is it (Option 1) a mixture absorbs all the range A absorbs and absorbs all the range B absorbs OR is it (Option 2) a mixture with original A and B pigments therefore some...

I have a source of electricity that's alternating but at variable frequencies. So an asynchronous alternating current of sorts if you will. Can industrial rechargeable batteries be charged like this efficiently? Or would DC current work best? Or normal AC?

Please can anyone help me on how to work this out ?

I have the following problem: "A box with a mass of 10 kg is accelerated by 10 m/s/s over a distance of 10 meters. What is the kinetic energy of the box (assuming no friction)" Using work... Work = K.E. F * D = K.E. m*a*D = K.E. = 10 kg * 10 m/s/s * 10 m = 1000 Joules However, using...

Coulomb's Law $$ \vec{F} = \frac{1}{4 \pi \epsilon} \frac{q_1 q_2}{r^2} \hat{r} $$ $$ \vec{E} = \frac{1}{4 \pi \epsilon} \frac{Q}{r^2} \hat{r} $$ Let's say we want to find electric field with a distance r from charge Q. How does permittivity effects the magnitude? Will I choose the permittivity...

i can't manage to grasp the concept of PV work in thermodynamics, for example we all know that W= integral(F*dx) like here but this says that, at the end, W doesn't really depend on the gas temperature or reversible process crap at the end W is simply a constant, atmospheric pressure is...