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Hot answers tagged temperature

7

The noise is either from the AC electricity, which would be a 60Hz buzzing, or from small bubbles forming on the heating element itself. When the electricity stops, both the buzzing and the bubble formation will stop as well. Bubbles create sound due to quickly expanding from a small nucleus. Here's a book I found with a section on noise from bubble ...

3

Negative temperatures are only defined for systems where there are a limited number of energy states. Consider rising the temperature of such a system, then as the temperature starts rising, particles begin to move into higher energy states, and as the temperature continues rising, the number of particles in the lower energy states and in the higher energy ...

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If you rearrange your equation to solve for $Y$, $$Y=(X+125)\frac{-30+70}{360+125}-70$$ This reduces to $$Y=\frac{8X-5790}{97}=0.08247X+59.6907\approx0.08X-60$$ which is about what the textbook obtains. The difference in values you are getting is completely due to the approximation that the solution manual uses. If you use the exact values, as you did, ...

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Is tossing out ice that forms in the buckets overnight helping with that efficiency, or are we actually throwing out valuable sucrose that could be made into syrup. There's an easy way to test: take a sample of the discarded ice, melt it, measure the volume $V$, evaporate it until only solids remain, weigh the solids, and compute the percent dissolved ...

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There are many problems : $1.$ As pointed out by Olin, gas cannot exist as a gas at $0 K$. $2.$ In ideal gases, interaction between molecules are absent. Hence, there is no potential energy. Remember that Potential energy always has an additive arbitrary constant. $3.$ As pointed by Wojciech, you would need (to take}energy to cool that ...

2

The expression $$k_B \frac{\Omega}{\bar{\Omega}}$$ equals $$k_B\frac{1}{\bar{\Omega}}\frac{d\bar{\Omega}}{dE}$$ which equals $$\frac{dS}{dE}.$$ In thermodynamics, where $S$ is the Clausius entropy, this is equal to $1/T$ where $T$ is the Kelvin temperature. In statistical physics, this expression can be taken as a definition of $1/T$ of a system from ...

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If You know density $rho_r$ at some temperature $T_r$, there is a following formula for density: $rho=rho_r[1+b(T-T_r)]$, where $rho$ is the density at temperature $T$ and $b$ is called coefficient of cubical expansion, evaluated at reference temperature and density ($rho_r$ and $T_r$). It is valid for liquids.

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The key point I'm getting at is that when the pressurized liquid moves through the throttling valve, the auto-refrigeration effect is really a way of splitting the hot vapor "part" away from the cold liquid "part". I think this is the main misconception you have. Typically when a material boils, the gas that is released is at roughly the same ...

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I think that the simplest way to wrap one's head around negative temperatures is that one: $$\beta = 1/T$$ The point is -- it is much more "physical" to describe a temperature of a body in terms of $\beta$. (We are using inverse of $\beta$ for a number of practical and historical reasons, but nevertheless.) The larger that quantity $\beta$ -- the lower the ...

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Each mole of sucrose in a kilogram of water would depress the freezing point of water by 1.85 degrees C, according to Blagden's law (which is more valid at low concentrations). The molecular weight of sucrose is 342 grams/mole. So 2% sucrose should freeze around -0.1 C and 10% sucrose -0.5 C. Fractional freezing of grapes increases sugar concentration ...

1

Your kettle needs incoming energy from the heating element to turn water in to steam. Steam bubbles forming and collapsing make the familiar sound. Early on many of the steam bubbles don't make it to the top because they cool off when they rise away from the heating element. This is why the familiar rumbling sound starts way before the water boils. The ...

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Law of equipartition predicts the heat capacity of gases correctly. It assumes that inter-molecular attraction in gases is negligible (which is true). But for solids, inter-molecular attraction is not negligible, the, how come it still predicts the correct value for molar heat capacity? You have to know what "negligible" means in the context of the ...

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Normally when compressing a gas the temperature increases. If you assume adiabatic compression, the law is $PV^\gamma=k$, where $\gamma=\frac {C_P}{C_V}$ is the ratio of specific heats and is usually about $1.4$ for air. Then, as shown here $\frac {T_2}{T_1}=\left(\frac {P_2}{P_1}\right)^{\gamma-\frac 1\gamma}$ This assumes you don't leak heat to the ...

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temperature is the measure of speed of molecules. when you compress the gas molecules start moving faster, which is the same as saying the temperature increases. why do molecules start moving faster? there are many ways of explaining this. here's one. when molecules are squeezed into a smaller volume their location is now more certain, it's locked in a ...

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