Hot Definition and 560 Threads

Homework Statement A Hot air balloon is traveling vertically up- ward at a constant speed of 2.6 m/s. When it is 19 m above the ground, a package is released from the balloon. The acceleration of gravity is 9.8 m/s^2. After it is released, for how long is the package in the air? Answer...

I have 2 problems that i can't do You apply a force of 0.35N up to lift a fork. The resulting acceleration is 0.15m/s2 up. Determine the mass of the fork (the answer is 35g-why?) A hot air balloon has acceleration of 1.10m/s2 down. The mass is 315kg. What is the upward force on the...

was just watching this video(The joy of science) on thermodynamics, and the proffesor of the video said "hot objects don't always accelerate." this went against what i previously thought. tried googling it but couldn't find an answer. i don't know how to picture this. how?

How might hot jupiters arrrive close in, since gas sufficient for their formation would be seem to be further outward? It might seem to require a 3-body 'solution'. That is, must another gas giant have been in the mix for much earlier stages? Perhaps ejecting 1 giant, and retaining the other in...

Homework Statement A hot-air balloon is descending at a rate of 2.0 m/s when a passenger drops a camera. If a camera is 45m above the ground when it is dropped, (a) how long does it take for the camera to reach the ground(b) what is the velocity just before it lands? Let upward be the...

I can't find my favorite tea anymore so I am looking for a new one. I'm looking for something without caffeine so I can drink it before bed. I also want something that is available in a tea bag; loose teas are too inconvenient. I tend to like fruity and tangy blends, and sometimes, spice...

Very hot question(Answering will get you 5 dollars, just kidding. Because Earth's rotation is gradually slowing, the length of each day increases: The day at the end of 1.0 century is 1.0 ms longer than the day at the start of the century. In 24 centuries, what is the total (in hours) of the...

If you suddenly put your hand into very hot water it feels cold (or atleast, it's hard to tell if it's hot or cold) for the first second. Why is this so? Thanks.

I'm interested in the physics behind racing Hot Wheels cars. When you release the cars from an incline, what makes some cars go faster than others? What would be the most important factor of a fast car (ex. weight, aerodynamics, etc.)? How could I modify a car to go faster? Thanks!

I'm looking forward to tasting some of turbo's habanero sauce. :-p

I'm a chemical engineering undergraduate studying in Canada right now. I'm not too sure what my future looks like, so I'd like to have some opinions on whether it's a good engineering discipline to stick with. 1. I'm interested in a career in R&D, but I hear that you need at least a PhD. I'm...

As we all know, core body temperature is around 98.6 degrees Farenheit. It is more comfortable for one to wear less clothing when the temperatures are in the 80s and 90s (since this allows core body heat to more easily disperse outside). But what if the temperatures are in the upper 90s and...

http://news.yahoo.com/s/ap/20070701/ap_on_sc/rethinking_nukes There is also fervent anti-nuke opposition waiting to be re-stoked. Jim Riccio of Greenpeace said nuclear advocates are exploiting global warming fears to try to revive an industry that's too risky to fool with. "You have...

"glow" of emission lines vs. hot objects I was wondering how the mechanisms differ between the following two scenarios: A. The glow of emission lines (I think it has to do with the Bohr atom) B. The glow of hot objects (I think it has to do with Blackbody radiation)

"glow" of emission lines vs. hot objects I was wondering how the mechanisms differ between the following two scenarios: A. The glow of emission lines (I think it has to do with the Bohr atom) B. The glow of hot objects (I think it has to do with Blackbody radiation)

Is there any reason why most hot things alost always begin to get the tinge of red??

Hi all, Sat this problem in an exam recently and it's got me wondering. First off, you have a reservoir at a lower temperature T1. You also have a mass of water at a higher temperature T2 (in this case it was 10C and 100C, I can't remember the mass but let's say it was 1, and Cv 4.2). First we...

Hello people :smile: Again I need some help...:shy: I'm looking for a type of cloth that can be used to seal a gas at up to 700 degrees C (about 1200 F) and a pressure difference of up to 1 atmosphere. Just to explain a bit more, I want to seal gas between two sections of a jet engine...

This cute mechanical engineer mentioned in a message that he had designed some manifolds, so that's why I'm asking this (in addition to my general interest in physics, of course). I'm not sure if they were intake or exhaust manifolds, but that's not the problem now. I figured that...

http://www.twilightus.net/adam/weather.gif :cry: :cry:

I will be writing my final exam tomorrow evening, and I am currently stuck on the following practice problem. It would be very nice if someone could help me out and I will remain eternally grateful for your help! 1) (Multiple Choice) Which of the following statement(s) about Cold Dark Matter...

A particle of mass 12 grams moves along the x axis. It has a restoring force F= -0.06 N/m. If it starts from x=10 cm with a speed of 20 cm/sec toward the equilibrium position, Find its amplitude, period, and frequency. Determine when the particle reaches the equilibrium point for the first time...

To start things off i am using DSC (Dipsersion Strenghtened Copper) 99.58% copper 0.19% Aluminum Oxide 0.16% Oxygen Less than .01% Iron Less than .01% Lead max tensile is about 10 breaking pounds or 88ksi i think for...

Hey guys, I'm new to these forums so I'm hoping i have posted this question in the appropriate thread. Recently, i noticed the electric heater in my fish tank had a volume of water around it all times which was rising, it made sense to me that the water surrounding the heater would be rising...

I play around with HO slot cars and would like to wind my own "hot" armatures but I can't find any sources of direction. It seems like everyone knows how to do it so why explain:frown: I've bought a couple of pounds of mag wire in different guages but I would hate to tear up a good one to...

Can someone briefly explain the definition or the difference between a cold and hot transition of light? Hot transition involves a change in an atoms vibration and standing wave patterns from absorbtion of higher frequency, such as skin sunburn from long exposures to ultraviolet light or...

everybody knows that hot air rises. but on thinking about heat as the knetic energy of molecules, heat transfer just becomes another word for collisions between molecules (looking at a gas) right? so surely hot air, in it's attempt to rise from the bottom to the top of a container, would...

I would think that after 4 billion years the thing would stabilize and cool off. I can't imagine that this is all due to continental drift and what not. Could there be an enormous nuclear fission furnace at the center of that iron core? Does solar wind drive an electric current in the center...

1. A woman informs her engineer husband that "hot water will freeze faster than cold water". He calls this statement nonsense. She answers by saying that she had actually timed the freezing process for ice trays in the home refrigerator and found that the hot water does indeed freeze faster. As...

I've always wondered how people are able to walk on hot coal without suffering from burns. Moreover, earlier, a teacher demonstrated to my class how if one spills liquid nitrogen on one's hand in open air that one does not suffer from frostbite, but only feels the cold temperature. I got...

Here I've seen different solutions. Some people simply add a T to the hot water pipe from the heater and run the circulation pipe alongside the hot water pipe connecting the two near the end. They then connect a pump to this. I don't really see how this has any effect. Wouldn't the hot water...

Good morning everbody, very good indeed. Well, tell me what you think : http://dorigo.wordpress.com/2007/01/19/a-21-sigma-eccess-of-mssm-higgs

In your opinion what are the top specializations of EE that are in demand. What is the hardest to get into and yet most rewarding? I've taken some introductory courses in the following subjects and done pretty well. Right now I see myself going into Analog but I am so interested in RF. Is RF...

I'm looking for a way to estimate the size of hot water accumulators for residental buildings. I have made myself graphs describing the varying demand of hot water during a typical day, and then compared this to a graph describing the production rate of new hot water. This is according to a...

Hi all! Could anyone tell me, a final year student in mechanical engineering preparing for his final year project, what the hot reserach topics in heat transfer are?

Is "Global Warming" hot? What is your sense of public awareness of and the attitudes towards this subject? It seems to me that in the US we have finally reached critical mass. Since to a large extent TV merely feeds people what they want to watch and what they already believe, and since TV...

Is it normal for air conditioners to completely suck when you need them to not suck? It's 107 today and its been around 85-88 degrees up here where the air conditioner is. Do air conditioners just fail to work after it reaches a certain freaken temperature or something? Our filter is newly...

The Mpemba effect is about the phenomena of hot water freezing faster than cold water. Does anyone know how to pronounce Mpemba?

I usually use an average number of 2 kPa friction loss for normal tap water in pipes. Does anyone know if this number changes significantly up or down for water which is around 80 degrees C instead of 5?

Direction of heat? "Hot to cold..." Please explain. During a college prep class last year, my physics teacher said something about the direction of heat. He asked a student, "Which direction does heat go? From hot to cold, or cold to hot?" I'm pretty sure that's what he asked. I wish I had...

http://arxiv.org/abs/astro-ph/0505036 http://www.universetoday.com/2006/06/12/gigantic-ball-of-fire-discovered/ the popular news item says "gigantic-ball-of-fire-discovered" heh heh it is a gas cloud in the cluster Abell 3266 which is hot enough to be observed in Xray wavelengths----ie...

Is it true that if you take the same food, same amount and everything except one serving is heated and another is not. Would the person eating the heated serving get more nutritional value from it in the form of more energy? This comes about from the larger potential energy stored in the bonds...

Recipe: -First, heat up your pants really hot, then add oil. -Put the cabbages in salt water. Then sit in the sink until the morning. -Next, chop all the vegetarians into little pieces. -Next, add a little Buddha and mix it all up. -When you are finished cooking, find a suitable bowel...

What do you think the hot topics in maths will be in the future? I can only speak from an applied point of view, but perhaps someone else could come in from the pure angle... In the 90s, I think the hot topic was ''Chaos Theory'' ( http://en.wikipedia.org/wiki/Chaos_theory ) - even banded...

Hey so I am stuck on a 2part question, it goes as follows: A tungstan filament in a light bulb is rated 75w for a 230v supply. The resistance of the filament at 20*C (*C means degrees celcius) is 68 ohm. Assume a constant temperature coefficient of 0.005. Calculate: A) The hot resistance...

This was a question posed to me by a homeowner. I don't know very much thermodynamics and hope someone here might have a better understanding. They have a run of 3/8in copper pipe leading from their water heater to various taps. On cold mornings, it takes a long time, for hot water to flow to...

Consider a spherical hot body having a temperature T, located on one of the pans of a very sensitive balance. It is equilibrated puting a given mass on the other pan of the balance. The temperature T is lower then the ambiental one. The balance is in mechanical equilibrium but out of thermal...

A thing i have noticed when burning paper on an open fire, the paper has burnt, and left a carbonized sheet, every so often a red hot thin thread travels along it, even on a very hot roaring fire the sheet will stay intact for several minutes, but what are these red hot threads burning.

A spoonful of sugar is dissolving in hot water. The initial mass of the sugar was 7 grams and 5 minutes later the mass present had halved. The mass of sugar, S grams, at time t minutes after it was placed in the hot water can be modeled by S(t) = S0e^−kt, t ≥ 0. b Find the exact value of k...

This subject came up in HRW's thread about dating, but I didn't want to drag it off-topic. The question is, what do you mean when you use the words in the subject heading, specifically when in reference to someone of sexual potential? This topic seems to have come up in conversation with...