Hot Definition and 572 Threads

I've always wished i could figure out how to calculate this. But don't know where to start. scenario: you have to boil a liter of water. if you fill it with cold water from your faucet, it will bill in X amount of time. if you fill the water with hot water from the faucet, it will boil...

Homework Statement A heat engine is taking identical amounts of heat from two hot reservoirs at temperatures ##T_{H1}, T_{H2} ## doing work and then heat to a cold reservoir ##T_C ## What is the maximum efficiency of this heat engine? Homework Equations For a Carnot cyle it is ## \eta = 1 -...

Alright, let's see what ideas everyone comes up with on this question. I'm no optics guru, so I'm hoping you have better ideas than me. Here's the situation: I have a column of hot gas wherein every gas molecule emits radiation over 4π sr. At one end of the column I have a window where emitted...

HI i am a student from Singapore , and i was told to calculate the amount of hot water needed to supply to a house. The design brief stated 1)Deliver 15 gallons of water at average 110°F (43°C) temperature within 10 minutes; 16 water draws during 1 week 2)Dishwasher: Successfully wash five...

Can someone give me a non-technical explanation of a mutational hotspot? What exactly is it and what causes it?

I bought a ravpower brand laptop power adapter half year ago,it works well before,but this week i find it will become very hot,I don't know why.But I am thinking maybe it is relative with the time of using or the voltage?Or some other problem?Sometimes I play games for all day and I have a bad...

Dear Members, I am trying to calculate how quickly hot air cools in a stainless steel pipe. The details are as follows: • a stainless steel pipe conducts hot air with temperature at the top end of the pipe of 85oC (185F). • the pipe is 10m long and passes through 5m of ambient air with...

Lets say, we have a cathode that emits electrons into the space under field emission and create a space charge in air.There is no arching of electrons to anode.We have hot dense gas which blow on space charge in certain direction.What would be the most likely outcome of interaction between...

I found this explanation here: Food that sticks is caused by chemical bonds that form between the food and the material of the pan - almost always a metal. These bonds may be relatively weak van der Waals forces or covalent bonds. Protein-rich foods are particularly prone to sticking because...

This is from a physics textbook All objects radiate energy continuously in the form of electromagnetic waves due to thermal vibrations of their molecules. These vibrations create the orange glow of an electric stove burner, an electric space heater, and the coils of a toaster Is the orange...

Like absolute zero, is there an absolute maximum temperature?

This is killing me because I used to know how to solve this problem, and I can't remember how to make it work. Its been too long since I took a physics course. I will be placing some plastic sheeting near a 1000W lamp. I want to calculate how hot the sheeting is going to get, to make sure its...

In my chemistry class today we learned about equilibrium and how temperature affects the equilibrium constant. An example that was cited was this chemical equation: H2O <--> H3O+ + OH- I learned that increasing the heat of the water will drive the equilibrium toward the right side...

Naming "Hot Stuff"... All of you who know me and the ones who follow my posts but don't know me, I would like to ask your humble advice and input for seven hot pepper sauces, 2 mild, 2 medium, 1 hot, and one extremely hot. Sounds easy right ? Not quite. I want names that the unscientific...

I was trying to calculate possible orbit of a potential exomoon of a hot Jupiter within habitable zone of a red dwarf. Everything (heat absorbed, reasonably within Hill sphere, far from Roche limit) seamed reasonable. However, I encountered one problem - hot Jupiter should be tidally locked. It...

Homework Statement Estimate the average temperature inside a hot-air balloon. Assume that the total mass of the unfilled balloon and payload, which we will all call mp is 500kg. Homework Equations Archimedes principle, ideal gas law ... The Attempt at a Solution Okay I'm not really...

My potential supervisor is SO hot! long time no see... I just have to let this out somewhere. and Here is the only place I can do this! forgive me! So... OMG! SOOOO HOTTTTTT! OHMYGOD! lollollol ok, so I'm on the course, and we have to choose supervisors for our projects. so I've been...

Hi Does the color of a hot body depend on its material composition ? For eg. will bodies made of steel, Stainless steel, Ti, Cu etc. all look red in color if the temperature is ~ 550 deg C ? TIA

Thanks. Why do wires get hot as current flows? Is it friction?

Hello all, i was wondering this i doubt it but would it be possible to somehow replace the heat in hot air with electricity to make the air rise like it was heat but it's not? I would like to know if this is somehow possible I'm a bit of a noob on this so any help would be good thank you.

First , i am sorry if i posted on a wrong section because I am just new here . We , as a group of four ,need some ideas on constructing a hot air balloon with maximum diameter of 50cm (for balloon) and it should be powered only by candle (made or bought) with maximum of 3 wicks for our Physics...

Homework Statement You cool a 100g slug of red-hot iron (temperature 745 degrees C) by dropping it into an insulated cup of negligible mass containing 85g of water at 20 degrees C. Assuming no heat exchange with the surroundings, what is the final temperature of the water? Homework...

Hi this is probably very easy for you guys, but I can't figure this out. Heated air rises right? Then why is it that when I put a bowl of soup in the microwave and heat it in a plactic Tupperware-like container, then remove and cover it -- does a vacuum like effect occur? It would seem to me...

I had some of this given to me as an exmas present, and i can tell you it is hot, what i need is a recipe that i can include it in, any ideas welcomed .

When you heat the gases inside a hot air balloon it makes more sense (for myself at least) to say that it rises due to the velocity and kinetic energy of the molecules in their relation to the gases outside. Outside the balloon the molecules are obviously cooler, more dense, and moving slower...

Why water heated with electric heater remains hot for long time than water heated by gas stove

Hey Guys, I really did my best to locate the best sub-forum for my question (I was hesitating between the Homework one and this one), so please bear with me if my choice is wrong ... Now to my question: So in my kitchen, I have a hot plate appliance, and it says on it that power...

Upon reading about this galaxy I was curious about the gas surrounding it. This galaxy is a field galaxy so is not under the influence of any nearby galaxies. It is elliptical so I do not think it has any average rotation. It is approximately 40,000 parsecs in diameter and is surrounded by a...

I've heard of something called Absolute Hot...the opposite of Absolute Zero (Absolute Cold). What happens at Absolute Hot?

I got this app Thermal Light and I wanted to know the temperature of my fireplace before I did some marshmallow roasting.

I was reading about cellulose derivatives there and came across the wiki page for methyl cellulose: https://secure.wikimedia.org/wikipedia/en/wiki/Methyl_cellulose which states that it is a hydrophilic compound that dissolves in cold water but not hot water. Up until now, every compound I've...

Hi, I was watching a hot air balloon show, and one of the demonstrations was someone dropping a ball out of a rising hot air balloon. If a hot air balloon is rising at let's say 19.6m/s, and you drop a ball directly down, will the ball continue to rise for two seconds because it has an...

Homework Statement why are there crystals formed when a hot saturated solution is allowed to cool? the solid has already dissolved into the solution, forming the solute, so when the solution is cooled, and the temp decreases. does this mean they dissolve out of the solution? (i know...

Homework Statement A hot air balloon has just lifted off and is rising at the constant rate of 1.6 m/s. Suddenly, one of the passengers realizes she has left her camera on the ground. A friend picks it up and tosses it straight upward with an initial speed of 10.8 m/s. If the passenger is 2.5 m...

Do the sentence "when the sun is shining then it is hot" is a logic sentence ?

I was wondering whether an induction hob cooker would work in reverse if a hot pan is placed on the coil - so would this generate a current? I would assume not as the heat induction pan wouldn't be able to create a magnetic field in the coil?

Hello all, I am conducting some experiments in which the samples are to be produced via hot pressing. However, I have been unable to produce flaw-free parts (e.g., parts exhibit pancaking and crown defects). I'm not sure what modifications to the load schedule or die assembly should be made...

Homework Statement A 100.0 g copper sample (specific heat 0.385 J/g K) at 100 C is added to 50.0 g of water at 26.5 C. What is the final temperature of the copper-water mixture? Homework Equations q = q(copper) + q(water) q = (heat capacity)(change in Temp.) q = (specific...

Homework Statement A hot air balloon is traveling vertically upward at a constant speed of 3.4 m/s. When it is 11 m above the ground, a package is released from the balloon. After it is released, for how long is the package in the air? The acceleration of gravity is 9.8 m/s^2. Answer in units...

Like on a hot day, cars make these clicking sounds on the surface? Does having a silver or white-colored car make it worst? Because I've seen black -colored ones do that too

This morning I went to the dentist and when she shot me up I was startled to feel that the metal body of the hypodermic was hot when rested it against my lip. I stopped her and asked if she had heated up the novocaine. She said it wasn't hot, merely warm, and proceeded with the shot without...

Hi Here is the physics problem that I could not figure out: Hot air balloons float in the air because of the difference in density between cold and hot air. Consider a balloon in which the mass of the pilot basket together with the mass of the balloon fabric and other equipment is m_b. The...

Her family knew she was doing this and didn't take her for psychiatric care? http://www.suntimes.com/news/metro/7558632-418/woman-dies-after-injecting-hot-beef-fat-into-her-face.html I'm thinking that the bacterial infection she died from could be related to the infection in her face...

Homework Statement A shipyard worker drops a hot steel rivet (mass 125g, temperature 350 degrees C) into a river at temperature 5 degrees C, a distance 30m below. Stating any assumptions you make, calculate the entropy change of the universe as a result of this event. (specific heat capacity...

Homework Statement A man wants to go on a hot air balloon trip, and wants to build a balloon with a capacity of 10,000 m^3. The envelope and the balloon have a combined mass of 250 kg. His luggage would be 800 kg. Assume that the ambient air is at a temperature of 20 degrees Celsius. What...

i did a search in the forum and no posts on this.. question- will drinking hot tea cool you down?? ...it does have caffeine..if i remember correctly, caffeine opens your arteries ...it is a diuretic... is there any emperical data or does anyone have any knowledge of lab experiments?

I noticed recently that hot chocolate when left on the table for a while and starts cooling at room temperature, starts getting thicker (more viscous). However, when it was put in the fridge overnight and got completely cold it became more liquid (less viscous). Why does this happen? Can someone...

Homework Statement A hot air balloon of mass M has two forces acting on it. An upward lift force and its weight due to gravity. The balloon is initially accelerating at a rate of -g/3. A)Find the upward lift force in terms of the initial weight Mg. B) What fraction of the total weight...

Would you like the 105 F we had yesterday? I'll trade.

what is the temperature of cold & hot dark matter?