what boils faster hot or cold water??
494092
As any sane and decent person would expect, hot water out of the tap will boil faster than cold water out of the tap. However, water that has been boiled once and allowed to cool will boil faster than hot water out of the tap. That's because boiling gets rid of the dissolved oxygen usually found in water, making it easier for the water to boil the second time around.
1017824
Hot water will drop in temperature at a faster rate, but the cold water will freeze first except under certain circumstances in a phenomenon known as the Mpemba Effect\n\nhttp://math.ucr.edu/home/baez/physics/General/hot_water.html\nfor more details on the phenomenon
209491
On a mountain top the air pressure is a little lower.  If you ever went on top of one you might be one of those unfortunate souls who suffers from altitude sickness, gasping for breath.  Strange how a little less pressure and a little less atmosphere can effect us so much.\n\nAnyway, back to cooking.  At higher elevations water boils at a little lower temp than 100 C.  What this means is that if it boiled say at 80 C you cannot get it any hotter, it is boiling already.  So say you wanted to cook some spaghetti.  If you put your spaghetti in a cold water in a pot overnight, eventually it would get soft enough to eat.  It would be cold, but you could eat it.  On a mountain, cooking takes longer because  it is like cooking on medium heat instead of leaving the burner on high.  Either way it will cook, one will take longer than the other.
280538
Hot...In an open container of skating rink, hot water evaporates more quickly and thus cools more quickly.  At sufficiently high temperatures, evaporation is more important, if equal masses of water are taken at two starting temperatures, more rapid evaporation from the hotter one may diminish its mass enough to compensate for the greater temperature range it must cover to reach freezing.
259920
Well this depends on the quantum of hot water consumption as well as the heating element capacity or power. If the consumption is more and the heating element is not so power full you will have situation of flowing hot water 1st followed by normal water (or cold)then the hot water again (if using tank less) however if u got an element with immense power it will turn the normal water to hot as soon as the water enters in the tube (heating chamber), same situation can be occurred with a tanked one if the tank's water storing capacity is not much. By the way what i experienced is; maintenance point of view "tanked ones are preferable". (I assume you are asking about water heaters for the home)
240544
Absolutely, yes.  PURIFIED water can become super-heated in the microwave -- that is, above boiling temperature but not actually boiling.  Tap water has minute particle in it that will facilitate the normal boiling process. Purified water does not, or it doesn't have enough.  When the surface is broken with a fork or spoon, for example, the built-up heat energy (that should have been causing the water to boil) will then pop causing the water to explode out of the container.
662532
Hot water will drop in temperature at a faster rate, but the cold water will freeze first except under certain circumstances in a phenomenon known as the Mpemba Effect\n\nhttp://math.ucr.edu/home/baez/physics/General/hot_water.html for more details on the phenomenon
766842
1. microwaves heat water faster than boiling it over a heat source.\n\n2. microwaves have a more direct effect on an atom, since the energy is transferred directly form the MW to the atom, unlike the boiling water where it is transferred from heat source to water to the thing (w/ enzymes). the longer path means longer time.\n\n3. since the atoms (or molecules for enzymes) directly interact with the MWs, they are more likely to be destroyed than when boiling water is used. Hence the shorter time to ensure deactivation, and not destruction, is achieved
797128
How long? That depends on the pressue, how warm/cold the water already is, and what you're trying to boil it with.
893761
Using the particle theory of matter, the movement of particles in any matter (i.e. one that has mass and occupies space) increases (i.e. particle speed increases) with its temperature.\n\nWarm water has a higher a temperature than cold water.  Hence, the particles in the warm water move at higher speeds than that in cold water.  Moving at higher speed means having greater kinetic energy.  Thus, easier for the particles to break the inter-molecular forces present among the particles in the liquid to travel into the air.\n\nBy the way, this question should have been placed under the physics field.
509639
the cold water cools down the hot water, and the hot water warms up the cold water until they are at the same temperature....lukewarm water
1163536
The definition of freezing is that they reach 0C, not that they turn to a solid, that is a separate step.  Hot water pipes and cold water pipes, both in an identical freezing environment will cool down at different rates because the higher the temperature gradient or difference, the faster the rate of cooling.  So hot water will cool faster to 0 than cold water, although cold water will form ice faster since overall it requires less heat overall to be removed to freeze.\nNote that practically the hot pipe will take longer to freeze solid since there simply needs to be more energy removed to get the solid.  This question is normally asked theoretically to demonstrate (or trick a student) to teach the lesson about how larger temperature gradient have a higher cooling speed relative to the lower temperature gradient.  It depends on the reason for asking this question.\n\nNote that the Mpemba effect, while it has been observed, is only under specific experimental conditions and is far from a general phenomenon and not general enough to effect the average set of pipes in the average house basement.
46526
it doesnt, however the energy is lost faster in hot water than in cooler water.  The rate at which all water freezes is the same.
745215
The answer is yes. And I bet you want more of an explanation, which gets a little tricky. It would seem evident that cold water would freeze faster than warm water. But there have been raging debates in scientific circles over whether that's true or false. The fact is a lot of different factors contribute to how fast water freezes, including its beginning temperature.\n    Physicists writing in the journal Scientific American have waded into the fray and have probably come the closest to a satisfactory answer. Quoting Paul G. Hewitt in the book Conceptual Physics, the Scientific American writers believe that hot water will freeze faster than lukewarm water, but not faster than cold water. (Except under certain circumstances.)\n    According to Scientific American, water at 90° C will freeze before water that is 60° C. Below 60° C, however, there is a switch and the cooler water will freeze faster. For example, 30° C water will freeze faster than 60° C water. It has to do with the water evaporation of the hot water immersed in a cold environment. The rate of cooling by evaporation is way higher for hot water than for the cooling of lukewarm water.\n    Now, for those certain circumstances. When you put a pan of cold water and a pan of hot water in a freezer (both pans have equal masses of water), the hot water experiences this rapid evaporation AND freezing from below, which cools water on the bottom of the pan. Because the surface water is already warm or hot, the water at the bottom just sits there instead of rising, getting colder and colder. The water at the top experiences evaporation. The combined effect could make the hot water freeze faster than the cold water.
34255
I would have to say hot water.
638380
Heat will always travel from the warmer to the cooler. For example, an ice cube might be 32 degrees. If it is sitting in a room with an air temperature of 70 degrees, the heat in the air will travel into an ice cube until it melts completely. Once it melts, the water it was made of will continue to absorb the heat in the air until it is the same temperature as the air. The same occurs with oil in an engine, or any other object. Some things absorb or lose heat faster than others, and the more of a temperature difference there is, the faster the heat travels from the warmer object to the surrounding air, water, or whatever. An ice cube will melt much faster in boiling water than it will in cold water. Water will also freeze faster the colder the freezer is. I have proven this a number of times by putting room-temperature water bottles in various freezers. Some freeze in less than an hour, some freeze in several hours, depending on the freezer's temperature. Here's a conversion for Celsius and Fahrenheit.\n\nConvert Fahrenheit to Celsius F=1.8(C)+32\n\nConvert Celsius to Fahrenheit C=(F-32)/1.8 \n\nTo answer your other question, it has nothing to do with how many degrees per gallon of water in order to freeze it. What is important is that the air temperature is below freezing. The farther below freezing the air is, the faster the water will freeze. The more water there is, the longer it will take to freeze. The warmer the water is, the longer it will take to freeze. There are several variables. The volume of water, the temperature of the water, and the temperature of the air. It is the same for motor oil, or any other liquid. The rate of heat transfer is different for everything.
673796
Boiling water has a temperature of 100 Celsius, steam can have higher temperature.