explain why a glass jar can be opened more easily if the metal lid  is heated gently first.?
109071
Molecules do not expand.\nIncreasing the temperature of a material increases the speed at which its molecules move - the molecules take up more room and the material expands a little.\nHeat energy is conducted better in metals than glass so the temperature of the metal lid will increase more quickly than that of the glass. The metal lid will expand more quickly than the glass, consequently the lid can be removed more easily.
59308
Contrary to what some science teachers and tour guides may say, glass is NOT a "slow-moving liquid". That's an urban legend.\n\nMany years ago, the method of making glass panes involved spinning a glob of glass on a flat disk until the glass flattened, which caused the outside edge to be thicker than the center. When the disk of glass was cut into panes, one edge was always slightly thicker.\n\n"Estimates of the viscosity of glasses at room temperature run as high as 10 to the 20th power Scientists and engineers may argue about the exact value of that number, but it is doubtful that there is any real physical significance to a viscosity as great as that anyway. As for cathedral windows, it is hard to believe that anything that viscous is going to flow at all.\n\nIt is worth noting, too, that at room temperature the viscosity of metallic lead has been estimated to be about 10 to the11th power, poises, that is, perhaps a billion times less viscous-or a billion times more fluid, if you prefer than glass. Presumably, then, the lead caming that holds stained glass pieces in place should have flowed a billion times more readily than the glass. While lead caming often bends and buckles under the enormous architectural stresses imposed on it, one never hears that the lead has flowed like a liquid."\n-Dr. Robert Brill, Corning Museum of Glass\n\n\np.s. \n\n1. The more viscous a liquid, the higher its resistance to flow - not the other way around. \n\n2. It's "Newtonian", not "Neutonian".\n\n3. Although glass exhibits characteristics of both liquid and solid, it's categorized as an amorphous or "pseudo" solid.
352065
some is reflected by the glass, and some passes straight through.  A tiny part will go towards heating up the glass itself, as it is absorbed during its transition throught the glass.
43501
Its a Metal, hence responds to / is a conductor of heat.\n\nIts fluid so the expansion per gradient of heat would be highest.\n\n\nAll other liquids are not a conductor of heat ( or as good as mercury)
116361
It depends on the temperature at which you are talking about. At room temp glass is a solid. However, at a high enough temperature, glass can be in liquid form, much the same way that ice melts into liquid. It just takes a lot more heat. To clarify from one of the other responses, it is liquid as long as it is in it's liquid phase. Steel is still called steel, even when it is molten enough that it's flow properties are similar to that of water. However, as we interact with steel and glass it is in it's solid phase.
330815
"Each hob contains one or more coils made of ferromagnetic material. When an alternating current is passed through these coils, a magnetic field of the same frequency is produced. If a magnetic-based pan is placed on the hob, the magnetic field induces a current in the pan. The internal resistance of the pan causes heat to be dissipated, following the Joule effect. Thus it is the pan itself, and not the cooktop, that heats up and cooks the food. Once the pan is removed from the cooktop, the energy transfer stops. The result is a flame-less method of cooking in which it is nearly impossible to start a fire by forgetting to turn off the stove. Parents won't have to worry about their child touching a hot burner because the cooktop surface remains cool. Changing cooking temperatures is achieved quickly because there is no wait for the hob to heat up, only the pan. Since there is no transfer of heat energy between the hob and the pan, less heat is lost into the air, resulting in a more efficient means of cooking, not to mention a more agreeable cooking environment."\n\n\nhope that help?  we just renovated our kitchen and have installed a Miele induction cooktop and it works wonderfully.  It provides much greater control over temperature...and I am still shocked at how quickly water comes to a boil.  Who knew a stove would be so exciting? haha.
448803
Put a rubber stopper or a lid on the glass jar.  You can turn the jar anyway you like, nothing will fall out.
1003680
The lamp consists of an illuminating bulb, and a glass bottle containing a transparent liquid, translucent wax, and a metallic wire coil. The glass bottle sits on top of the bulb, which heats its contents. The metallic wire coil is hidden in the base of the lamp, which the glass bottle is sitting on.\n\nThe wax is slightly denser than the liquid at room temperature, and slightly less dense than the liquid under marginally warmer conditions. This happens because the wax expands more than the liquid when heated.\n\nThe light bulb heats the container at the bottom, and due to heat exchange with the atmosphere, the container eventually dissipates the introduced heat. This method of heat transfer is called convection.\n\nWax at the bottom heats until it melts, and eventually becomes less dense than the liquid above it. At this time, a portion of the wax rises towards the top of the container. Near the top, away from the heat source, the wax cools, contracts, and as its density increases it begins to fall through the liquid towards the bottom of the container again. The difference in temperature between the top and bottom of the globe is only a few degrees.\n\nOne mass of wax may rise as another falls. The metal coil at the bottom helps to overcome the surface tension of the individual wax droplets, causing the descending blobs to agglomerate into a single molten wax mass at the bottom of the container. The cycle of rising and falling wax droplets continues so long as the bottom of the container remains warm and the top of the container remains cool. Operating temperatures of lava lamps vary, but are normally around 60 °C (140 °F). If too low or too high a wattage bulb is used in the base, the "lava" ceases to circulate, either remaining quiescent at the bottom (too cold) or all rising to the top (too hot).\n\nChaotic behaviour makes the movement of the wax unpredictable—hence lava lamps can aid in the generation of one-time pads for cryptographic use.\n\nThe colour of the wax and the liquid often varies and can be found in many different combinations.
131245
It DOESN'T! The ice makes room for itself when the glass fills with water. Melted ice takes up less room that solid. So when it melts, the volume in the glass is the same.
423110
because the atoms are packed more tightly together
280487
The idea behind fractional sterilization --- in which you heat, cool, then heat again to sterilize a container --- is to catch resistant microorgranisms and spores that survive the first heating.\n\nCertain microorganisms and spores are actually activated by the first round of heating, so if you serially heat, and then cool, it gives the resistant "bugs" a chance to germinate. Once they're "out in the open," you can kill 'em off with a second or third round of heating.\n\nThis site below doesn't completely explain the difference, but it does go through a lot of the general ideas behind sterilizing instruments and other things in a hospital setting.\n\nTake a look...
11832
The heat capacity of the tile floor is much lower than the air. In other words, it takes less heat to change the temperature of the floor than it does to change the temperature of the air. It's the same concept as taking out a rack of cookies from the oven. You can touch the cookies because they aren't that hot, but you avoid the metal rack because its heat capacity is much lower than that of the cookies.
598272
it makes the container stronger and less likely to dent or crinkle.
283659
Because the bottle is not really empty, it is filled with air.  The air expands when it is heated because the molecules move faster, bump against each other, and require more space.
115731
Now this is just good business sense my friend. Decreasing the glass size by half cuts the cost for manufacture, and it also maintains the same contents. Brilliant!
106734
It depends on the relative humidity. The location with more relative humidity will cause more "sweating" or condensation on the outside of the glass. \n\nThis will usually be indoors, since it is usually drier indoors, thanks to air conditioners in the summer, and heaters in the winter.
970807
what they're finding out is best to heat food in a glass container than plastic containers in the microwave.