how could hot water help you unscrew a jar's lid that is on tightly?

Answer 1

The coefficient of expansion is greater for metal than for glass.

Answer 2

The glass in the jar and the metal in the lid expand at different rates. The idea is the hot water will cause the metal lid to expand more than the glass jar. When a ring is heated and expands the inside diameter increases. This is why the metal band around wooden wagon wheels were heated before the wheel was assembled. When the metal band cooled it contracted binding the entire wheel together.

Answer 3

Specifically, the metal in the lid is affected by the hot water, and expands the lid a bit, while the glass of the jar is not affected

Answer 4

Metal expands and contracts more in respons to heat and cold than glass does. By running hot water over the lid the metal will have a tendancy to expand more than the glass does. This decreases the amount of pressure between the glass and the lid allowing it to turn more easily.

Answer 5

Because heat speeds up the molecules in the jar and causes the lid to expand.

Answer 6

Because hot air is less dense (takes up less space) than cool air. When you heat the jar, the air inside kind of shrinks. Which takes pressure off the lid, allowing you to twist it eaiser.

Answer 7

It could help the metal lid expand just enough to loosen it.

Answer 8

Metal expands with heat.

Answer 9

the hot water lets pressure go in the jar.... it creates gas in the jar (like steam) and that lifts it up

Answer 10

simply because when things heat up they contract and when they freeze they expand. so if u heat it it will contract and make it easyier to open the lid.