Why is it easier to open a lid with hot water?

The hot water helps the metal expand, therefore loosening the lid and making it easier to unscrew.

Why does running a hot water over a tight metal lid on a glass jar makes it easier to open?

Applied to a metal jar lid, this implies that the inside diameter of the lid will increase, tending to loosen the lid. Directing the stream of hot water at the center of the lid heats the metal more than the glass, so that you get a greater difference in the expansion of the top and the jar.

Why does hitting a jar open it?

It is two fold. You dent the lid enough to loosen the seal between the lid and the top of the jar. This reduces the friction between the two. Secondly, you release some air into the jar to relive some of the vacuum.

How much force does it take to open a jar?

The average normal and tangential forces applied by the thumb to the jar lid show that the normal force is the primary contributive force for opening a jar. This normal force is approximately three times the tangential force.

Does cold water make metal expand?

Metals dont expand while cooled(as far as i know) . Even fluids and liquids shrinks due to reduced activity of molecules under low temperatures . Atoms vibrates at higher temperatures . Hence ,it expands also each metals has its own coefficient of expansion.

Why do we keep a stuck metal lid of a bottle under hot water?

Metals expand on heating and on losing heat, they contract. So when we keep the container in hot water for a while, the metal lid expands and thus makes it easier for us to open it.

Is cold water corrosive?

Corrosion in water systems due to dissolved oxygen commonly takes the form of deep pitting rather than a general attack of the entire surface. Even where there is little or no corrosion in the cold water lines of a home, a high corrosion rate may exist in the hot water system.