- #1
Hot metal lid on cool surface has resistance when pulled up
In summary, when a hot metal lid is placed on a cool surface, the air inside cools and creates a vacuum, causing the lid to form a seal with the surface. This creates resistance when trying to lift the lid, as demonstrated by the boiling water sounds heard. This phenomenon is also seen with hot coffee mugs on laminated surfaces, posing a potential safety hazard.
- #2
sophiecentaur
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Hot lid from saucepan with water on the underside and hot air underneath. Lid put on cool surface. Air inside cools and pressure drops. Water forms a seal round the outside.
Nature abhors a vacuum. (There is a more Scientific version of the final step
)
It happens with hot coffee mugs on laminated table top and can make you splash coffee all over the table when you try to lift it to drink. Whoop whoop safety hazard.
Nature abhors a vacuum. (There is a more Scientific version of the final step
)It happens with hot coffee mugs on laminated table top and can make you splash coffee all over the table when you try to lift it to drink. Whoop whoop safety hazard.
1. Why does a hot metal lid have resistance when pulled up from a cool surface?
This is because of the phenomenon known as thermal expansion. When metal is heated, it expands and when it cools down, it contracts. As the hot metal lid comes into contact with a cool surface, the outer layer of the metal cools down and contracts while the inner layer remains hot and expands. This creates a tension between the two layers, resulting in resistance when the lid is pulled up.
2. Is this resistance the same for all types of metals?
No, the level of resistance will vary depending on the type of metal used. Some metals have a higher coefficient of thermal expansion, meaning they will expand and contract more significantly when heated and cooled. This will result in a higher level of resistance when the lid is pulled up.
3. Will the resistance decrease if the lid is left on the cool surface for a longer period of time?
Yes, the longer the lid stays on the cool surface, the more the metal will cool down and contract, reducing the tension between the layers. This will result in a decrease in resistance when the lid is eventually pulled up.
4. Can this resistance cause damage to the lid or the surface it is on?
In most cases, the resistance will not cause any damage to either the lid or the surface. However, if the lid is made of a particularly brittle or fragile metal, there is a possibility that the tension created could result in cracks or damage to the lid. It is important to handle hot metal lids with caution to avoid any potential damage.
5. Is there a way to prevent or reduce the resistance when pulling up a hot metal lid?
One way to reduce the resistance is to let the lid cool down for a short period of time before attempting to pull it up. This will allow the metal to contract and reduce the tension between the layers. Another option is to use a tool, such as tongs, to grip and lift the lid instead of using your hands. This can help reduce the risk of injury and minimize the resistance experienced when pulling up the lid.
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