When you inflate a bike tire, does the temperature change as you are inflating, or does it remain constant?
956387
Ideal gas law PV=nRT, which means Pressure x Volume = constant x Substance x Temperature.  The n remains constant and the Volume increase is so small that we'll say it is constant too.  That leaves us with P = RT, we know the R (substance) goes up since you are filling the tire with air, but we have two variables left, and depending on certain conditions the temperature or pressure can go up or down.  For that you would need to apply the second law of thermodynamics (entropy, simply stated if you put something hot next to something cold, the cold thing will get hotter and the hot thing will get colder, not vise versa) If you use hot air to fill the tire and the rubber from the tire is cold, the temp will go down (which will also decrease the pressure), if the air is colder than the tire the temp will increase (and so will the pressure).
769685
How about, does a cooler stay colder if you drain the water out of it continually or if the water is never drained.\n\nOr, does the density (amount) of seeds in a pot affect the amount of time it takes for the seeds to germinate?
838291
Good question!\n\nFirst law of thermodynamics states that the internal energy change ΔE of a system is equal to (Q - W). Where Q is the heat absorbed by the system and W is the work done BY the system on the surroundings.\n\nNow, as you already might be knowing that work can also be expressed in terms of pressure and volume as-\n\nW = PΔV (where P is pressure of the gas inside the system and ΔV is the change of volume)\n\n[Here: "system" = balloon; and "surroundings" = refrigerator]\n\nAnd as the change in volume (ΔV) in the case of balloon stated above is negative i.e it deflates, work must be negative i.e (minus W).\n\nNow, as Q is also negative (heat is given off by the balloon), the equation of First Law of thermodynamics reads-\n\nΔE = -Q - (-W)\nΔE = W - Q\n\nNow, if the balloon was large in volume, the change in internal energy ΔE would be positive and the balloon will either burst or move frantically in the refrigerator shelf.\n\nBut, if the balloon was a small one, it'd slowly become limp and deflate as the Q will overpower W (PΔV) in the equation and the internal energy ΔE will decrease and become negative.\n\nPlease note that I have made a lot of assumptions here that perhaps, might not be so easy to apply practically.\n\nThe points you'd have to consider are:-\n\n1-How tightly the balloon is wound so that air doesn't leak out of it.\n2- Whether or not there's a leakage in the balloon.\n3- The temperature of the balloon.\n4- The material of the balloon.\n\nStrictly speaking, the first law isn't even applicable in this case because the condition in the law is that the system (balloon) shouldn't be allowed to move. Its kinetic and potential energies should both be zero which clearly is not the case with our experiment.\n\nI hope this answer helps!\n\nGood luck!
142406
Mass is not affected by temperature, but volume can be slightly changed because if an object heats up, the particles begin to move faster and so it expands, or vice versa if the object gets cooler.
738632
What do you mean by the outlet temperature not being uniform. Do you mean not the same over time? Or are there multiple outlets and the temperature from each outlet is not the same?\n\nIf the inlet and outlet channels or headers are not designed carefully to allow for good fluid dynamics then there can certainly be portions of the exchanger that is not getting the same flow as other portions.\n\nWithout more information, I can not see how an energy balance will help solve the problem.
703096
Charles' law states that, under constant pressure, the ratio between a gas' volume and absolute temperature remains constant.  So if it heats up it expands and if it cools it contracts.  For example, you fill a balloon with helium at room temperature, and then put it in a refrigerator.  The helium will contract, and the balloon will shrink.
148133
ok, the relationship between altitude and temperature is not constant.  at sea level it is on avg 288.26 kelvin.  the temperature falls as you get higher until you are at about 11 km at which point the temperature remains constant.  the temperature fromm 11 km through 25 km from sea level is 216.66 Kelvin.  and then after 25km it starts getting warmer as you get higher until you reach 47 km and then it again becomes constant, this time at 282.66 kelvin and stays constant until 53 km.  after 53 km it continously gets colder again.  And if you go really high, it just keeps getting warmer again after 90km as you leave earth and enter space because then there is nothing between you and the the full force of the suns energy.  So if you go high enough, between 47 and 53 km, it is actually not that much colder than on the ground.  these temperatures and altitudes are based on standardized data, meaning that it is not going to be exactly the temperature everywhere at a given altitude, just like it is not 288.66 kelvin everywhere on earth, they are standardized avgs., but when engineers design airplanes, these are the numbers they use.  \n\nthe reasoning for all this is a combination of what everyone else has already mentioned.  it is the result of density, distance from the earth, radiation, etc.  See, at sea level it is warmer b/c the atmosphere traps the suns energy.  as you get higher, you get further away and it gets colder since the atmosphere it thinner(less dense) and doesnt trap as much heat.  then it levels off and starts getting warmer because the atmosphere is thinner.  this time the thinner atmosphere doesnt block as much of the suns energy and radiation, causeing it to get warmer again.  then once you get really high, it just keeps getting warmer as you enter space.  other factors are that the composition of the air changes with altitude, like the o-zone layer for example, is different from the air at sea level.\n\nhttp://mintaka.sdsu.edu/GF/explain/thermal/std_atm.html\nhere's a link to a graph showing how the temperature changes with altitude.  you can find tables with the exact values used to create the graph in engineering textbook or the internet as they are very common
1068914
This kind of depends on the other conditions of your experiment.  By Boyle's law, PV=nRT, or pressure times volume = number of moles of gas times a constant times temperature.  Since your pressure goes up, the only way to keep temperature constant is to reduce the volume of your container by half.  Is that the condition of the experiment?  Your gas is in a piston chamber of some sort?  Generally, compressing a gas increases its temperature, so I suppose if you did this, you could measure the temperature beforehand, compress the gas and then wait until the gas cooled back down to the same temperature.\n\nIn any event, since temperature is simply the measure of the average kinetic energy of all the particles in a system, since kinetic energy itself is calclulated by knowing velocity and mass and the mass hasn't changed, at the same temperature, the gas molecules have the same average kinetic energy and therefore the same velocity, and since you don't specifically care WHICH direction they're travelling in, they are at the same speed.
344631
As far as the weight is concerned they are same.  But in a constant volume situation yes the hot air would weigh less then the cold air.  Hot air expands and therefore rises up in the atmosphere.
414472
HAHAHAHA You all forgot about our little friend called drag! Inside or out the ball has a drag force acting on it by the surrounding air. Like stated before the air in the car is moving with you, and the car, and the ball all the same and the drag force on the ball at this point is negligible. This is not the effect of a vacume, a vacume is the absence of air. is it possible for there to be no air in the car? NO, Sooo.. outside on a bike or where ever, you are traveling at a speed where the balls light weight will be significantly affected by this drag force and it will cause it to slow down as you throw it up and while you keep riding on un affected by the static(motionless) air, your ball only has one force acting on it, air drag causing it to slow behind you.   test this by throwing a variety of same shaped objects while riding and you will see that the one with the most density will keep up the best. try a marble V.S. a ping pong ball.  then do it in the car
1077010
All I can think of...\nGravity (weight of bike + person), friction (of ground and all axles), pedal force (not constant because you are pushing on an arc), air resistance, inertia (this is why it gets easier to pedal once you get to constant speed), sprocket ratio, gyroscope effect (makes it easier to balance).
489363
Yes, it remains constant, but is not constantly in the same form...ice melts, water evaporates, vapor condenses, etc.  But I think that overall the sum is the same...
1159227
As a general rule, warm air rises and cool air sinks\nit expands and becomes lighter as the molecules of air move farther apart
526702
The only way to know is to try it! Get one of those 12V compressors for inflating car tyres and connect to the bottle with a pressure gauge that reads +200psi. Cover the bottle with some sort of containment device like a laundry basket leaving the guage exposed so you can read it with a pair of binoculars. Turn on the pump and stand well back..!
691591
This all depends on the type of valve that you have.  There are two types of valves that you will find on a bicycle tire: schrader or presta.  The Schrader valves (http://en.wikipedia.org/wiki/Schrader_valve) are like the one you see on your car.  A presta valve (http://en.wikipedia.org/wiki/Presta_valve) is more narrow and are seen usually on road bikes with more aerodynamic rims.  Most pumps will handle the Schrader valves without any issues (including your gas station).  For presta valves, some pumps will accommodate them.  For those that won't, you can buy an inexpensive adapter at a local bike shop to place on the presta valve and use a standard pump (similar to this http://www.rei.com/product/27860.htm).  I always carry one of these adapters with my when I ride, in case I need to pull over at a gas station for air. You might be careful about how much pressure you put into a bike tire.  Different tires will support different pressures.  Too little pressure and you are opening yourself up for pinch flats.  Too much pressure and you could blow the tube or have a few uncomfortable ride.  Usually, anywhere between 90-110 is about average.
404977
Hahahahahahaha, how amusing the previous anwers are.\n\nThe balloon would continue to rise in the atmosphere until it reached a height where the pressure inside the balloon was equal to the pressure outside the balloon...then it would remain at the same height, moving in the wind, maybe slightly up and down due to thermals...until it burst !
317634
Pressure will increase if temperature increases, assuming that the container remains at a constant volume. Because the molecules are moving faster, they collide more often with the walls of the container, so the pressure goes up.\n\nThis is demonstrated by Gay-Lussac's Law, which states that that for a fixed amount of gas (fixed number of moles) at a fixed volume, the pressure is proportional to the temperature, so:  P/T = constant.\n\nIn case you need to know this for a test, and easy mnemonic  is "Pete and Tom are Gay" (Pressure and Temperature are proportional according to Gay-Lussac).