2006-10-23 07:38:57 · 12 answers · asked by yoyo 2 in Science & Mathematics ➔ Chemistry
The hot water causes expansion in the lid. This makes it easier to open the jar because there is less resistance from the lid.
2006-10-23 07:46:53 · answer #1 · answered by Amanda SSS 3 · 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.
2016-05-22 01:45:10 · answer #2 · answered by Anonymous · 0⤊ 0⤋
the metal lid will expand due to the heat, thus being less tight to the jar and proving easier to open
2006-10-23 07:41:10 · answer #3 · answered by Anonymous · 0⤊ 0⤋
The heat makes the metal expand, thus loosening the lid.
2006-10-23 07:44:55 · answer #4 · answered by James N 1 · 0⤊ 0⤋
Heat causes matter to expand. Glass and metal expand at different rates. The metal expands more than the glass, allowing you to open it.
2006-10-23 07:41:23 · answer #5 · answered by © 2007. Sammy Z. 6 · 0⤊ 0⤋
when you run hot water over the lid, yuo are symbolically making a sacrificial offerin to Origami ... the suni god of food packers. If this offering is found to be acceptable, the lid will be released. However, if you are not pure of heart and free with your body, the offer will be rejected and you will be forced to go hungry until penance is made by offering up your body to a member of the opposite sex.... trust me, I know this to be true!
2006-10-23 07:52:48 · answer #6 · answered by jeep_man129 3 · 0⤊ 0⤋
expands the metal making the lid larger. allowing the seal to brake
2006-10-23 07:48:19 · answer #7 · answered by norsmen 5 · 0⤊ 0⤋
The metal expands faster than the glass, so the cover can then be easily removed...OR If it's stuck due to a thickening of the material (chocolate-ketchup,etc) it may soften the material enough to allow the screw top to be removed..
2006-10-23 07:44:40 · answer #8 · answered by Wytchfinder I 1 · 0⤊ 0⤋
Heated metal expands, thermodynamics. The expanded metal then loses the tight seal it has against the glass.
2006-10-23 07:40:33 · answer #9 · answered by phantomlimb7 6 · 0⤊ 1⤋
When you heat metal it expands, ergo it loosens its hold on the jar.
2006-10-23 07:47:08 · answer #10 · answered by smoothie 5 · 0⤊ 0⤋