Temperature Definition and 1000 Threads

I am trying to find the temperature of a star given its wavelength in micrometres, but I am not sure if my conversion is right therefore don't know if the answer is correct. Star A has a maximum emission wavelength of 1 μm and Radius 100 Rsun. What is its Effective Temperature and Luminosity...

Homework Statement Imagine a wet thermometer whose bulb is covered with a wet wick at 1 atm. Temperature of the water happens to drop during the process of evaporation. Homework Equations N/A The Attempt at a Solution Does evaporation lower the temperature of water just by removing...

Could turbine exhaust temperature be negative Celcius? My calculations yield 176 K. Is that possible? Inlet conditions are 7.8 MPa and 625 K. Exit pressure is 1 atm. (100 kPa.)

Hello everybody I am an architecture student working on a facade system and because I do not have much physics knowledge I stumbled across a question I can't answer myself: If my facade is actually a thin parallelipiped glass tank filled with water, how do I measure the temperature changes of...

Hi folks, This is a question about how to calculate entropy change when there is a temperature change involved. I got the correct answer to this, but I don't actually understand why it's correct..! Any help is much appreciated. Homework Statement One mole of liquid bromine is heated from 30...

I am interested to use a pyrometer to measure the temperature of a graphite heater while it is being heated (upto 1200 degC). The heater is located inside a small chamber filled with liquid cyclohexane . For viewing purpose of the pyrometer the chamber is having a viewport of Quartz. The...

http://arxiv.org/ftp/cs/papers/0701/0701016.pdf The above is link of Kafri's paper I was just studying at high school when I found this theoretical scientific discovery proposed by an enough notable Israeli physicist Oded Kafri. He made a unique unification or link between second law of...

On the epoch of last scattering, the universe became transparent and the typical CMB photon was "free" to travel the universe. The corresponding radiation was of a black body temperature of ~3000K. My question is: after the last scattering, the universe was still hot and, I presume, emitting...

I know that peltier plates are for cooling(mostly :smile:) but I wish to try out heating other substances using peltier plates. I'm planning to use 3 peltier plates (TEC1-12712) [maximum temperature difference of 70 degrees measured at 25 degrees / Maximum temperature difference of 80 degrees...

I have learned that temperature is defined as the vibration of particles. However, in vacuum, there is no particles. In reality, no absolute vacuum can be done, so I can't find answer online. Do you think the temperature (in Kelvin) is zero or undefined? Thank you.

I just went out to my car to retrieve my laptop. My car is at about 1 degree C, my house is at about 20 degrees C. I soon noticed condensation forming on the screen and it occurred to me that condensation was probably forming inside as well on the electrical components. The combination of...

Does temperature depend on the kinetic energy, or internal energy ?? Does it only depend on the movement of the molecules, or also the potential energy of molecules??

Homework Statement A liquid is enclosed in a metal cylinder that is provided with a piston of the same metal. The system is originally at a pressure of 1.00 atm (1.013 x 105 Pa) and at a temperature of 30 °C. The piston is forced down until the pressure on the liquid is increased by 50.0 atm...

Homework Statement My questions are based on a graph. I am trying to figure out the standard ΔH change for the graphed reaction and the standard entropy change. (1) What is the standard enthalpy change for the graphed reaction? (A) -31 KJ/mol (B) 0 (C) +12 KJ/mol (D) +11 KJ/mol (2) What is...

is there a way to calculate the themperture of something like a fire, if you know the thermal energy it produces.

The HadCRUT4 global surface temperature anomalies in tabular form include confidence intervals. The GISS surface temperature data is available in tabular text form here http://data.giss.nasa.gov/gistemp/tabledata_v3/GLB.Ts+dSST.txt - but it doesn't include any confidence intervals. Can...

I plan on using a 1 ft long, 0.005" diameter platinum wire as part of an electrode. The wire will be bare but will be inside a hollow plastic tube that has an inner diameter of 0.08". It needs to be able to carry a maximum of 1 mA for a length of 10 minutes, while not exceeding 60oC. I'm not...

The measurement of electrical resistance as a function of the superconductor's temperature yields fundamental insights into its properties. The Critical Temperature, Critical Current Density, and the Critical Magnetic Field, can all be obtained through variations of a basic experiment. I would...

Homework Statement Na has a bcc structure with molecular mass of 22.99 gr/mol, mass density of 0.971 gr/cm^3. The average speed of sound in Na (at room temperature=300K) is 3200 m/s. Calculate the Debye temperature for Na Homework Equations I worked out this equation to calculate the Debye...

Homework Statement Two moles of an ideal gas undergo a reversible isothermal expansion from 3.37×10−2m3 to 4.29×10−2m3 at a temperature of 29.6 ∘C. What is the change in entropy ΔS of the gas? Homework Equations pV=nRT The Attempt at a Solution W=∫V2V1pdV, I don't know how to use this...

Hello there, this is a fact that I can't understand thinking about it... Energy has to be given so that the inter molecular bonds can be broken, and energy goes in when there are formed (even though that sounds very counter intuitive to me), but why is the energy all distributed to potential...

I wonder why we can find temperature (or pressure )when the other property value is given.Lets say we have a rigid tank, which contains 50Kg of water at 90 degree celsius. If we look up the thermodynamics table, we can find the saturation pressure 70.14 kpa and definite liquid and gas specific...

Hi All, I'm working on an automated chiller control system for final year project. It is a logic control that automatically set the chill water supply temperature based on current demand load and the chillers performance curve to achieve the best efficiency COP for the system. For a variable...

Hello, I'm reposting this 'cause I think it's more relevant here than where it was posted before. Not sure how to delete the other one... I'm trying to plot the heat capacity as a function of the temperature from some small temperature to Debye's using numerical summation over the energy (shown...

Hi all, so when you heat something up the molecules begin to move faster. This is seen when you steam a tea kettle. So my question is when its very cold outside and there is no wind, it is much more comfortable then when there is cold wind whipping about your body. If molecules moving faster are...

Hello. The measurement of electrical resistance as a function of the superconductor's temperature yields fundamental insights into its properties. The Critical Temperature, Critical Current Density, and the Critical Magnetic Field, can all be obtained through variations of a basic experiment. I...

Good morning everyone! My chemistry final is approaching and I have a few difficulties in the thermodynamics chapter. One of the things that are bothering me is the calculation of the temperature of phase change. We know that if a mole of ice at 273K melts, the entropy change would be...

I am trying to back-calculate the greenhouse effect on planetary equilibrium temperature for Earth (in the hope I can then attempt applying it to other calculations.) I know that the actual equilibrium temperature of Earth is 287.89K, +33K above the calculated equilibrium temperature: Teq = (Q...

To begin with, I am an enthusiastic but very amateur physicist. I am working on my knowledge by taking online open courseware, buying textbooks and doing all the questions. I recently bought Astrophysics of Planet Formation which is no doubt out of my league but I like to pick at it from time to...

Qn : https://www.dropbox.com/s/dpcws9q4bjpzvtp/20151123_112037.jpg?dl=0 Why is option A and C wrong or correct? My attempted answer : A :A is plausible as if the piston is suddenly moved inwards, the gas molecules bounce off the piston at higher speeds Since Temp proportional to rms speed...

Homework Statement A gas has the following equations of state: P=\frac{U}{V} \,\,\,and \,\,\,T=3B\frac{U^{\frac{2}{3}}}{N^\frac{1}{3}V^\frac{1}{3}} where B is a positive constant. The system obeys the Nernst Postulate (S tends to zero as T tends to zero). The gas, at a initial temperature T_i...

I understand there are quite a few GUT candidates. I also understand that among these candidates some are considered by the theoretical physics community to be more likely to be correct than others. I am curious about what each of the various GUT candidates predicts as the time (relative to...

Hello. I will be doing some experiments with boron steel. The idea is to heat a steel specimen (200x20x1,5 mm dimensions) to 950°C and then quickly transfer it from the oven to the die at room temperature. When the specimen reaches the steel die it will supposedly be at around 800°C. At this...

I want to know how easy it is to find or make a really dense liquid...perhaps 4000 kg per cubic meter at room temperature or lower. I need it to be easily made so that it can fill huge a huge volume like thousands of cubic meters. Is this even possible? Mercury is too dangerous and scarce...

Hi, I know that changes in entropy can be expressed as a function of temperature, specific volume, and pressure using the fundamental equations of thermodynamics: ds = du/T+pdv/T, where the changes in entropy can be caused by either changing the specific volume or the internal energy. I also...

Wood and Copper are heated upto a steady state condition which will have a higher average of temperature at points ? Please state your mathematical approach 1. Homework Statement Dimensions remain same for both the materials as well as the temperatures both are heated to is the same Homework...

I'm trying to deduce the differential equation for temperature for a triangular fin: I know that for a rectangular fin, such as: I can do: Energy entering the left: q_x= -kA\frac{dT(x)}{dx} Energy leaving the right: q_{x+dx} = -kA\frac{dT(x)}{dx} - kA\frac{d² T(x)}{dx²}dx Energy lost by...

Homework Statement Hi there. My question is more for clarification than a homework question. In my studies, I noticed that my MCAT study manual provides problems relating reaction rates and the effect that temperature and thermal energy have on a reaction. For example, a question asks: in an...

Can someone explain three wire and four wire RTD circuits in terms of how the lead resistances affect the voltage output ##V_o = \frac{R_3 V_s}{R_2 + R_3} - \frac{R_4 V_s}{R_1 + R_4}## Also, in the case of a three wire, what is the purpose of Lead C?

I know that When there is increase in temperature the molecules in a viscious liquid move further apart and this decreases the viscosity of the fluid. So does that mean the molecules are far apart in case of liquid and these molecules move further apart with increase in temperature. So a...

Hi! Could you help me to find the yield strength at temperature SA-789/SA-789 М.

hey i really need help with solving this question. 1. Homework Statement the problem is in one dimention x ( 2 plates with diffrent K joined together) for x=0 T=500 ( constat temp) 0<x<L - electric wire is generating heat that maintane the constant temp in x=0 ,it has K=40W/mK. L<x<2L - there...

Homework Statement I read about Joule's experiment proving the transformation of mechanical work into heat. But say I have a bowl with some water, and I start turning a spoon in it very fast, thus doing work - the water won't get hotter! What am I missing? Homework Equations conservation of...

First of all (and I know this is not the place I'm supposed to introduce myself,) I'd like to say hi to the forums. Now onto my question. For the past few weeks, I've been thinking about an idea I had. That idea was to use pure oxygen to oxidize a combustion reaction in an engine. I'm sure...

Hi, when we assume a obejct with increasing dynamics with increasing temperature, the longitudinal relaxation time T1 should decrease. Since we have, let's say at a frequency 100 MHz , more fluctuations of B0. Ok, then the transversal relaxation time T2 must increase with increasing...

Homework Statement A sample in a lab is maintained at a cryogenic temperature of -195 °F. The lab is a balmy 70 °F. Heat leaks into the sample at a known rate, Q leak, which raises the temperature. Provide a brief explanation of how you would determine the minimum power needed to maintain the...

Homework Statement Assuming no heat loss to the container or the environment, what is the final temperature (K) of a mixture of 9.28L of liquid 1 (density=1070kg/L & specific heat capacity of 4358J/kg/K) at 378K and 12.15L of a second liquid (density=1070kg/L & specific heat capacity of...

I know two formulas which is to do with change in temperature,first one is : Q=mc(T-t) and the second one is E=sigmaT^4. My question is the difference between these two and where we have to use either of these?

Homework Statement a) The peak intensity of light from the Sun occurs at a wavelength of 500 nm. Astronomers discover a nearby star, “Nus”, which is the same size and mass as the Sun, but has a peak wavelength of half this value. Is Nus hotter or colder than the Sun and by how much? Nus is...

Homework Statement The peak intensity of light from the sun occurs at a wavelength 500nm. Astronomers discover a nearby star X which is the same size and mass as the sun, but has a peak wavelength of half this value. Is X hotter or colder than the sun and by how much?[/B]Homework Equations...