What is decrease: Definition and 239 Discussions

I'm not entirely clear what shunt resistance is, it's fairly hard to find things on google which refer to it in the context of LEDs. So we did an experiment in which we measured the IV characteristics of InAs at different temperatures, and observed the gradients of these graphs (apparently those...

What is the proof of the fact that for an isolated system, entropy can never decrease?

Pressure can exist in a container of gas even if there is no gravity. From kinetic theory of gases it is assumed that pressure exists due to momentum transfer between molecules and the wall. Suppose I have a closed container on Earth at sea level filled with air. Now I carried it to zero gravity...

I recently posted a statement that according to the 2nd law of thermodynamics, entropy always increases in a closed system, no matter how small the time interval is that one looks at. I think that is true for classical thermodynamic models, please correct me if I am wrong. Does quantum...

me and my friend were talking on facebook and we couldn't think of an answer to the question, would water pressure decrease in zero G, you can see how far along we got before getting stuck in the picture belowhttps://www.physicsforums.com/attachments/105576

Since a black hole goes to a singularity, theoretically wouldn't added mass to that point decrease the spacetime curvature by increasing of the circumference, and then not have a loss in information.

How can a electrons energy levels increase, and decrease in eV As atoms come together to form molecules the energy levels of electrons change in eV, but are there other ways a electrons eV can change. Can heating a material change the electrons eV level, when visible light hits the electrons...

If dark energy density were to be very slowly decreasing, how will the fate of the universe be any different from the energy density being constant? Would not the energy density be completely dominant in the future even if it were to be very slowly decreasing?

As the flow rate increases frictional force increases but friction factor(Darcy,Fanning) decreases with Re. Can anyone explain what is the concept behind it?

I was given the following drag profile for a spacecraft upon reentry. I understand that the moment it enter's Earth's atmosphere it will be accelerated due to gravity and pick up speed which in turn increases drag however I don't understand why drag then decreases. Wouldn't density cause...

Okay so here is my idea, not really sure how well (if at all) it would work but I am wondering if it would be possible (assuming battery technology is good enough) to ionise air in front of a formula 1 car (or plane or whatever) giving it a charge (like the way lightning works) , then creating...

Homework Statement We have: I=nAve Imagine a copper wire with a constant current through it: I=constant e=constant n (for copper)=constant Hence, we obtain: A is inversely proportional to electron drift velocity. My question is: how does that make sense? Why would the cross sectional area...

Homework Statement Show that the internal energy at constant entropy and volume decrease for a spontaneous process Homework Equations F = U-TS The Attempt at a Solution Use Clausius: dS-dQ/dT > 0 Assume constant volume: TdS > dU assume constant entropy this becomes 0>dU Since dU is...

Homework Statement f(x) = (x3 - 1)/(x3 + 1) Homework Equations (d/dx)[f(x)/g(x)] = [f`(x)⋅g(x) - f(x)⋅g`(x)]/[g(x)]2 The Attempt at a Solution f`(x) = [3x2(x3 + 1) - 3x2(x3 - 1)]/[(x3 + 1)]2 f`(x) = 3x2[(x3 + 1) - (x3 - 1)]/[(x3 + 1)]2 f`(x) = 3x2(2)/[(x3 + 1)]2 f`(x) = 6x2/(x3 + 1)2 When I...

When I download a book to my Kindle, does the total entropy of the device decrease. I would think so.

In hawking radiation a black hole decreases in mass and is described by E= mc^2-GMm/r and as r gets closer to zero the energy of the particle that enters becomes negative and takes away from the net energy of the black hole. My question is why does this only apply to these particles that pop out...

Homework Statement Helium is stored in a tank initially at temperature To and pressure Po. It starts coming out through an opening (pipe outlet) at a constant mass flow rate of mdot. Calculate the decrease in temperature and pressure of the tank (assuming no heat loss to the surroundings) as a...

Hi, I understand that a n type doping will increase the number of electrons, and those electrons will go to the conduction band since the valence band is already filled. I don't exactly understand the effect on the bandgap. Thanks!

Hi, I faced problem with the decrease the level of the batteries for UPS system and from time to time i filled the batteries but still the level decrease after one week... what is the problem and solution؟ best regards,

Hello, I have a cart going down an air track with an inclination of 7 ° and for some reason my acceleration is going on a downward trend, my velocity is increasing and naturally so is the time. to find velocity I'm using v = (2x)/t and for acceleration I'm using a = (2x) / (t^2). Can you tell mr...

From the equation for Z from this website...

In my book it is stated.When you keep the intensity constant and decrease the wavelength the photoelectric current decreases but I can't understand why? I thought it would stay the same since photoelectric current depends on the intensity of photons as more number oh photons means more e- released

I know that radial force comes into the play but the direction of gravity (9.8) is also the same as radial acceleration so instead it should increase on equator

Homework Statement Find the intervals of increase/decrease. Use first derivative test to find the local maxima and minima. Sketch a rough graph. Homework Equations a) f(x) = 2x2+12x-1 b) f(x) = 1/2x4-2x2 c) f(x) = 3x-4 sqrt 2 d) f(x) = x2-1/x2+1 The Attempt at a Solution A) it becomes f...

Hi everyone. Could anyone help me solve this. I need to find the increase and decrease intervals of f(x) = sin(-3x). The increase intervals of sin(x) are -\pi/2 + 2\pi*k < x < \pi/2 + 2\pi*k Is the following the right way to solve my problem (for increase intervals)? -\pi/2 + 2\pi*k < -3x <...

Seems like an easy question yet I can't find an answer. Obviously the surface layer of the ocean gets more sunlight but I don't think that is the reason deep water is colder. The increase in pressure usually increases the temperature but this seems to be the exception. Thanks for taking the time...

Homework Statement In which of the following cases does the internal energy of the described system increase: (I) A clay ball is dropped and sticks to the ground (II) Hydrogen and oxygen react exothermically to form water (III) A car is driven at constant speed (consider the effect of air...

I'm shopping for a battery-powered USB charger. Someone on Amazon says that as current (amperes) increases, battery life decreases exponentially. He says that using a charger with a current of 500mA gets you 30% more total power from the AA batteries than if you used a charger with a current...

It is my understanding that on earth, a hotter object surrounded by colder air will decrease in temperature because the faster moving atoms in the hotter object are repelled by the slower moving atoms in the colder air. This isn't worded very well, I hope you know what I mean. By what mechanism...

I know there are many factors that go into this. But in general how would one go about calculating the angular velocity for a car going up an incline. What I want to know in particular is if a car say is driving at a consistent speed of 60mph on an even plane and then hits an incline up wards at...

I believe I understand that you cannot directly connect watts to lumens because although they could/may be related, they represent different quantities (I guess it's akin to comparing height and weight measurements for a person). However, given the same exact light bulb, typically the higher the...

Hey, I'm looking at amplitude decrease of a seismic pulse as a result of geometrical spreading. Starting with I = E / (4 * pi * r2) where E = original energy from source, we know that energy falls off as 1/r2, thus amplitude falls off as 1/r. From wikipedia: "The energy or intensity...

Hey guys, Need some more help again. I'll keep it brief. This thread is only for question one. Please ignore 2ab. I started off by computing f'(x) via the product rule and calculating the zeros, at which point I got: x= 1/√ 5 and x=√(3) However, I'm at a loss as to what I should do...

Two ways of cooling a (real) gas are exchanging heat or doing external work. Let's assume we have a fixed volume of gas that does no work nor exchanges any heat (with surroundings i.e. adiabatic). Is it possible for such a gas parcel to cool at all? Or heat up? My intuition says no. An...

Hello I am curious, why is the heat if mixing negative? Why would mixing decrease the enthalpy?

Hi! Recently I have began to read up on my passion in physics in my spare time. I have encountered an experiment where lasers are used to decrease the speed of sodium atoms. The lasers are a wavelength that the sodium atoms absorb and then proceed to emit a photon. If the atoms are traveling...

density of normal water -1 gm/cm cube and density of soap water -0.9 gm/cm cube. We know that the addition of soap or detergent decreases the density of water. Thus If we keep on increasing the concentration the soap in the water does the density of water decreases gradually or remains...

Hi, Does anyone know or could help me understand the reasoning for the amount of slip within an induction motor decreasing with frequency under the same load conditions? I.e. For no external load, the slip is higher at 50Hz than at 20Hz etc? Thanks

From Statsitical And Thermal Physics (Reif. international edition 1985) 160 page. (5.4.4) S(T,V;√) = √[∫{cv(T`)/T`}dT` + Rln(V) - Rln(√) + constant] (integral is from T0 to T , cv is specific heat) This is a entropy of system for temperature 'T' , Volume 'V' , Moles '√' <--...

Hello, Do living beings use food to decrease the entropy of his body? If so, could anyone explain the process of how we do it? (or at least name a couple of keywords that I can search) Thank you very much.

Homework Statement So in one of our practice problems it states that as we increase the doping concentrations, the result will be a decrease in mobility. However, I thought that when you increase doping concentrations, there will be a higher concentration of carriers available for...

Hi all I am using the Kalman Filter with an EM algorithm, (schumway and stoffer). From my understanding the log likelihood should monotonically increase. In some instances however I obtain a decrease in the log likelihood, What can I infer from this? Has anyone experience of these...

Dear all, I would like to ask: Given a control volume (V1), at an initial temperature (T1), the pressure (P1) in the volume (V1) is decreased by sucking out air. The suction hole is then closed to achieve a state of P2 * V2 = n2 * R * T2 . What would happen to the temperature in the control...

What happens to a circuit over a resistor that causes measured voltage to drop? If voltage is related to a charge imbalance creating electric potential between two points, then what does electrons moving through a resistor have to do with a reduction of that charge imbalance? Series circuit...

I'm a bit confused because the sun's radiation & heat are passing through space (with some passing through planets' atmospheres), and there is almost nothing in space, therefore, how does that immense heat & light just diminish over AU distances when its going through almost nothingness? What...

Homework Statement Show that \frac{dp}{p} =\frac{\gamma}{\gamma-1}\frac{dT}{T} if the decrease in pressure is due to an adiabatic expansion.Homework Equations Poisson equations: Pv^{\gamma} Tv^{\gamma - 1} Ideal Gas Law: Pv=R_{d}T, where R_{d} is the dry air gas constant. Hydrostatic...

Hi Guys, So we have a melting furnace that is melting Aluminium. After 2 days of holding a melt to see how the furnace performs in a holding situation, I changed the PID control to have a longer sampling time and hence smoother control. What I noticed was the KW seemed to drop, although the...

Ok in metabolic acidosis, renal compensation is increase in aldosertone, which cause hydrogen and potassium excretion leading to hypokalemia. But in metabolic acidosis transcellular movement occurs and there is hyperkalemia. What is the final result for potassium level. Hyper or hypo?

Hi, If you give high doses of iodine thyroid hormone synthesis decreases. This means TSH level must increase. TSH function is to cause hyperplasia of the gland and increase vascularity of the gland. So how can iodine decrease vasculariy, when TSH is there to counter it. Thanks :smile:

Homework Statement For the function f(x) = x^3 - x^2 + 4x - 3 Homework Equations The Attempt at a Solution I found the first and second derivative, the first derivative is f'(x) = 3x^2 - 2x + 4 This is not factorable, as the discriminant is < 0, meaning there is no...