Temperature Definition and 1000 Threads

One is always told that a heat pump (heating water) should receive return water with a temperature as low as possible. I've never really understood why. My initial thought is that if the return is higher, then it's "easier" for the heat pump to heat the water up to whatever supply temperature...

Homework Statement A steel rod and an aluminum rod of equal length and diameter are placed end to end and secured so that they cannot flex. The rods are heated to the same final temperature, and the steel is found to increase in length by one-tenth of a percent. If the total length of the rods...

Hi, I'd like to know how I'd put together, either elegantly or at least in physical terms, that surely water evaporation in a large pool of V volume and S surface is influenced by wind (increased by it as opposed to having side barriers), temperature (increased by direct sunlight as opposed to...

Homework Statement Suppose you walk into a sauna that has an ambient temperature of 57.0°C. Calculate the rate of heat transfer to you by radiation given your skin temperature is 37.0°C, the emissivity of skin is 0.95, and the surface area of your body is 1.60 m2. I solved this first part and...

Good day every one! Based on my research as you increased the temperature, the grain size become bigger and the thickness decreased, but in some paper, thickness increased. The effects of annealing temperature is almost the same to the temperature. But if you will considering doping for...

I was playing around with numbers and found that the equivalent temperature for Hawking radiation from a Planck mass black hole is ~5×1030 K. Later, I saw that the Hagedorn temperature for strings (where the partition function is expected to diverge) is reported to be around ~1030 K. I thought...

Starting a car: the voltage drops from 12V to 7.2 V, it is 0 degrees out, and 150 amps are pulled from the car. What is the temperature coefficient of the resistor? I have NO idea how to do this. Help please!

I have several problems regarding this/these topics. Is anyone available to tutor me right now? Thank you.

Homework Statement a)a stationary railroad whistle is sounded. An echo is heard 4.0 seconds later by a train's engineer. If the speed of sound is 343 m/s, how far away is the reflecting surface? b) If the temperature of the air increased, how would this change your answer? Homework Equations...

Good day to all, Hi, i would like to ask if there is a way to calculate the temperature change at a given time. I will use this as a basis for my study which is about designing an ice container and i would like to know how long does my ice last given its own temperature and the outside...

My notes, using an example of a cold tube-side liquid cooling down a hot shell-side liquid stated that: ΔTb = TbS-TbT Mean tube-side wall temperature: TwT=TbT+(tube-side film resistance)/(total resistance) * ΔTb Mean shell-side wall temperature: TwS=TbS-(shell-side film resistance)/(total...

Homework Statement Suppose we drop a lead ball of mass M into water of mass m from a height h and allow everything to settle down. What is the temperature change of the water? Assume that the container is well insulated. Homework Equations Potential Energy = mgh dU = mcdT where dU is the...

Ok, so I could do an experiment on this first, but I decided to see if anyone knew beforehand. So basically my question is will different properties of the same temperature, exposed to the same temperature, cool/heat at the same rate? For example would a more viscous liquid cool as fast as...

Considering how hot brake rotors get under hard street and race track braking, what is the typical heat range experienced buy the actual wheel in contact with the rotor and hub?

Homework Statement An 8 cm3 ice cube (temperature = 0.00 °C) is dropped into a glass with 3 dL juice which results in the ice cube being melted. By doing this, the juice drops to a temperature of 3.00 °C. What was the temperature of the juice before the ice cube was added? (Treat juice as water...

I have a combustion process, and have calculated the net enthalpy of my inlets and outlets. Some of the energy released by the combustion is used to heat a cooling stream, maintained at temperature 46degC. I wish to calculate the power required to maintain this cooling stream temperature: I was...

At room temperature, particle energy is 0.025eV. Neutron capture reaction has big cross section when neutron is in room temperature. Theoretically, so does an electron. At 0.025eV, the electron velocity should be only 93.78km/s. Unfortunately almost no way to cool down an free electron to so...

Homework Statement 1 kg of moist air and 1 g condenses. What will the change in the temperature of the moist air be? Heat of Vaporization = 2.5*10^6 J/kg 2. The attempt at a solution The moist air will warm due to condensation. Heat of Vaporization=2.5*10^3 J/g Specific heat at...

Hi everyone, I am looking for basic elements resistivity vs. temperature laboratory measurements charts. Anyone has ideas where to look for? Regards

Mod note: moved from non-HW forum section Apparently doing math homework on Physics Forums helps me think more clearly. The d-part of this question gave me a headache, and I already wrote all of this LaTeX code on the homework side of this site, so I figured I'd post it even though I solved it...

Homework Statement I did an experiment involving the speed of sound at different temperatures. I placed two microphones at a fixed distance apart and I measured the time taken for a sound wave to travel between the two mics. I repeated this for different temperatures. I want to make a graph for...

Two Thermally insulated cylinders, A and B, of equal volume, both equipped with pistons, are connected by a valve. Initially A has its piston fully withdrawn and contains a perfect monatomic gas at temperature T, while B has its piston fully inserted, and the valve is closed. Calculate the final...

I want to know the what is the effect of temperature on modulus of rubber, mathematical expression will be helpful

Let's say that I have a spoon and a cup of coofee, I stir it with the spoon does its temperature decrease or increase ? (There is friction force so a bit of energy should turn into heat but it's strange).

Homework Statement Expose the error: When sodium is placed in water, a violent reaction always occurs; therefore sodium and water can never be at the same temperature. Homework Equations Thermal equilibrium and temperature. Zeroth law. Isotherms. The Attempt at a Solution My Answer: The...

Homework Statement I don't even know if this is the correct forum for this question, but here we go. This exercise is from my numerical methods for engineers class, and it says the following: The coefficient of saturation of oxygen dissolved in fresh water is given by the equation: $$...

Homework Statement A turbine is receiving air from a combuster inside of an aircraft engine. At the inlet of the turbine I know that T1 = 1273 K and P1 = 549 KPa, and the velocity of the air is essentially 0. The turbine is assumed to be ideal, so its efficiency is exactly 1. Also: R = 287...

Does any kind of polarized light transfer heat or any other form of energy? If possible give me some theory and related equation.

what does the relation between the temperature gradient inside the thermal boundary and thermal boundary layer thickness i mean what will be the temperature gradient ( high or low) when the thermal boundary layer is thick relative to the thin one? Kindly explain mathematically and physically as...

An automobile tire has a pressure of 210kPa at 20.0 degrees celsius. What will be the tire pressure after driving for some time if the temperature rises to 35.0 degrees celsius. The equations we have are P1*V1/T1 = P2V2/T2 V1/T1=V2/T2

What are two aspects in which the volume expansion of liquids and the volume expansion of gases due to a temperature change vary? Answer: One of the aspects is that gases can be more easily heated than liquids. This is because there are intermolecular forces (Van Der Waals interactions)...

After passing the thermocline, in which water temperature decreases rapidly over short distances, temperature falls into a sort of constant-looking decline. However, looking at the graph, it looks almost asymptotic. I've not been able to find a chart measuring water depths below 10,000m, so I'm...

Homework Statement The specific heat capacity of a metal at low temperature (T) is given as ##C_p = 32\left({\dfrac{T}{400}}\right)^3## (kJK-1kg-1). A 100g vessel of this metal is to be cooled from 20 K to 4 K by a special refrigerator operating at room temperature (27°C). The amount of work...

I know there are a few ways the universe can end, if it ever does, but at what temperature would the universe be in after heat death?

Does electrical arc with the same power but different voltage and current have same temperature? When electrical arc is form, it is estimate that the temperature is about 3000K Does temperature depend on voltage or current alone? Or does it depend on power(P=VA)? I think it is power, because...

Homework Statement Cooking gas containers are kept in a lorry moving with uniform speed. The temperature of the gas molecules inside the containers will increase, decrease or stay the same? Homework Equations T is proportional to KE of gas molecules. The Attempt at a Solution I thought it...

Homework Statement In a dark room with ambient temperature T0, a black body is kept at a temperature T. Keeping the temperature of the black body constant (at T), sunrays are allowed to fall on the black body through a hole in the roof of the dark room. Assuming that there is no change in the...

So I've been working at a steel mill where we deal with billets cooling from temperatures around 1200 C to between 10-25 C. I have access to average thermal expansion coefficients over this temperature range. First question: Over a large temperature range as aforementioned am I correct in...

Homework Statement For a home work assignment, I have to build a theoretical device which uses a laser to boil water. But I have no idea how to figure out how long it would take the device to transfer enough heat to boil the water. The laser diode has a wavelength of 445nm. We are supposed to...

Homework Statement Suppose the inner side of the annulus {(r,Φ): r_0 ≤ r ≤ 1} is insulated and the outer side is held at temperature u(1,0) = f(Φ). a) Find the steady-state temperature b) What is the solution if f(Φ) = 1+2sinΦ ? Homework EquationsThe Attempt at a Solution a) A =...

Homework Statement The Earth receives on average about 390 W m−2 of radiant thermal energy from the Sun, averaged over the whole of the Earth. It radiates an equal amount back into space, maintaining a thermal equilibrium that keeps the average temperature on Earth the same. Assuming the Earth...

Dear All, I have collected temperature data for a period of about 4 months with a device called ibutton attached to the surface of a concrete wall. My problem is the button is made of Stainless steel 305 and exposed to sunlight. I am interested in obtaining the wall surface temperature and at...

Hi everyone I searched about the mass flow rates and temperatures of exhaust gases of light gasoline internal combustion engine at different condition but I don't fond anything yet . Anyone can guide me? .

Can anyone explain to me why does temperature of water remains constant while boiling in an open vessel or in general sense why phase transition is isothermal in nature?please give me answers from thermodynamic point of view also.

A metal block at 500 K is kept on a large ice slab at 273 K.The metal block completely sinks inside the ice slab. I was told that the water in contact with ice would not change its temperature while the block sinks down and hence the "only" heat transfer from the metal block to ice slab will...

Homework Statement (This is not a homework problem, just something I'm curious about.) Assuming ideal conditions (clear skies, a flat landscape, no wind, anything else you can think of), is it possible to calculate how much the temperature (at 2 meters above the ground, as per meteorological...

Homework Statement A tuning fork with a frequency of 420 Hz emits sound with a wavelength of 0.82 m in air. If the temperature of the air increases, what will happen to the wavelength and why? Homework Equations The Attempt at a Solution I know temperature affects speed but I am not so sure...

Can anyone please answer this question? I have read that increased temperature increases entropy and increased pressure decreases entropy ,for a gas.And vice versa.decreased temperature decreases entropy and decreased pressure increases entropy.Can anyone please tell me for a gas under pressure...

Homework Statement A circular cylinder of height H is filled with monatomic gas molecules at temperature T. The cylinder stands on the surface of the Earth so that the gas molecules are subject to the gravitational field g. (a) Find the average height, z , of the molecules in the cylinder as...

hi i have a cylinder whose volume, intake and exhaust area is known. i know the amount of air entering into the combustion chamber(cylinder) and the amount of fuel entering into the combustion chamber. i am taking an ideal approach and assuming stoichiometric combustion (LPG). is there any...