why a glass jar can be opened more easily if the metal lid is heated gently first?
144979
metal expands when heated...hence the lid will become wider and easier to open...
152571
By heating the lid is bigger than it was, and bigger than the jar. So the lid is just seems like other bigger jar's.\nEven if you heated the metal lid and the gas together, you will get the same result, as jar's expansion is less than the lid's expansion.
1066122
The coefficient of expansion is greater for metal than for glass.
618505
your finger tips are used more often.\nit's easier to tell if an egg is about to break because you are squeezing it too hard, or if something you grab is too hot.
231746
So the lid can't fall in.
183943
I would say the thick glass. mainly because My roomate has destroyed many beer mugs making tea.  I would assume the reason is because the temperature is hotter on the inside than the outside  and this causes it to break.
907302
They are both transparent and water proof, which makes them good for storing liquids, and seeing how much is in the container.\nBut glass is much heavier and more brittle than plastic, which are both disadvantages for this use.
983144
interior of cup expands faster than exterior of cup due to poor thermal conductivity of the cup material.\n\nglasses that are thin enough will not suffer this problem because heat can conduct thru thin materials easily so that thermal expansion is more or less equal on the interior and exterior.\n\nyou can also force one of your glasses to break by cooling the glass with ice water, dumping the ice water away and then dousing the glass with boiling water. try not to hurt yourself.\n\nbicycle tire ruptures due to a simpler explanation. the tire cannot withstand increased pressures that occur when a gas is heated in a closed system. (gay-lussac law)
1172152
good obervation!\n\nwell the reason is that when anything dissolves in something, that anything has it molecular bonds broken and interrupted by the solvent molecules. now to break the bonds of the solute(which dissolves) we need energy. this energy is provided by the solvent molecules. \n\nnow when anything is hot it has more energy associated with its molecules. hence hot milk has more energy too. so.....when it has more energy itself, it can provide the sugar molecules with more energy, hence its bonds can be broken faster, hence it dissolves faster.\n\nhope ur satisfied.
766632
That makes the warm up operation slower.  Slower can be better because it causes less of a strain what is being warmed up.
32450
Yes.  You can form a supersaturated solution with salt and boiling hot water in a glass jar.  Tie a pencil to one end of a string and a paperclip to the other.  Allow the pencil to rest on the top of the jar so the paperclip can hang in the solution, almost touching the bottom of the jar.  Allow the jar to sit undisturbed and you'll see crystals forming within 24 hours.
858849
Easy. You heated the can, which means the air inside the can, including steam, was at a high temperature. That means it occupied more space. When you dunked it into cold water, the steam turned back into water, and the air in the can became more dense. The can crumpled because you basically created a vacuum effect. You decreased the volume suddenly by reducing the temperature.\n\nEnough?
709350
Solid in room temp, but melts in your hand (slightly above room temp)\n\nAlloys quickly with most metals.\n\nYou can read more at the following:
593090
the glass in your galsses is cooler then the air escaping from under the tissue. this will fog the glasses, much like coming in from outside on a cold day
262813
Heat leaves a bottle either through Convection, Radiation or Conduction.\n\nWith the vacume, you eliminate Convection and Conduction, because there is no air for the convection and the inner suface is in contact with the outer surface, and therefore no Conduction. The Silver Bottle reflects that radiation and preserves the heat even more efficiently.\n\nI hope you understood and thanks for making me revise my science class information.
145994
The metal spoon is a good conductor of heat. It also has a handle that protrudes out, with a fair amount of surface area to radiate heat out, and the spoon will also cool by convection. This definitely will cool the coffee down faster.
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.