2006-07-14 05:54:26 · 17 answers · asked by angel55_star 1 in Science & Mathematics ➔ Physics
metal lid expands making contact with glass less tight
2006-07-14 05:58:24 · answer #1 · answered by Robert A 5 · 0⤊ 1⤋
Glass Jar With Metal Lid
2016-11-15 04:53:43 · answer #2 · answered by heyder 4 · 0⤊ 0⤋
Aww, cmon people. A little physics here.
Expanding the lid won't help since it would just grip the jar better. What's happening is that the energy from the hot water is heating the lid which is transferring the energy to the contents, thus giving it more internal pressure as the molecules of the contents get excited by the added energy.
Most jars are vacuum sealed down to very low pressure, enough to keep the lid securely fastened by the pressure of air outside holding it down (since regions of high pressure want to equalize into regions of low pressure, the outside air wants to rush in, but the jar lid prevents that from happening, so the air simply firmly presses the lid against the rim of the jar, effectively sealing it).
Once pressure inside approaches pressure outside, there's no longer the vacuum effect and it's far simpler to open. Same reason that smacking the corner of the jar lid on the counter's corner and denting the jar lid makes it 'pop' and easier to open, it breaks the vacuum seal (leading to the characteristic 'pop' of air rushing in) and allows pressures to equalize. Thus there's not a greater pressure outside compressing the lid & holding the lid down and on the jar.
QED. Let's close this one.
2006-07-14 06:29:27 · answer #3 · answered by Michael Gmirkin 3 · 0⤊ 0⤋
Metal Lid
2016-12-26 11:58:41 · answer #4 · answered by Anonymous · 0⤊ 0⤋
The jar lid is metalic and the hot water causes a slight expanding of the lid, there fore allowing less friction and the lid becomes easier to remove.
2006-07-14 06:05:34 · answer #5 · answered by herbuncle 1 · 0⤊ 0⤋
The heat from the water expands the metal of the lid, making it easier to remove
2006-07-14 05:58:01 · answer #6 · answered by Mad Jack 7 · 0⤊ 0⤋
The metal lid expands much more quickly then the glass. This releases the binding of the lid to the glass threads.
2006-07-14 09:39:14 · answer #7 · answered by dbf320 2 · 0⤊ 0⤋
The heat from the water causes the metal to expand ever so slightly, releasing it from it's tight fit on the glass jar.
2006-07-14 05:57:58 · answer #8 · answered by therego2 5 · 0⤊ 0⤋
The heat from the water causes the metal to expand enough to make it easier to open.
2006-07-14 05:57:51 · answer #9 · answered by vonwasden 3 · 0⤊ 0⤋
the heat from the water builds up a pressure that makes the lid easier to take off.
2006-07-14 05:58:31 · answer #10 · answered by Jade A 2 · 0⤊ 0⤋
The metal lid will expand faster than the glass since the coefficient of thermal expansion is different for different materials.
2006-07-14 05:58:06 · answer #11 · answered by galactic_man_of_leisure 4 · 0⤊ 0⤋