If you heat a thin, circular ring in the oven, does the ring’s hole get larger or smaller?
When the lid of a glass jar is tight, holding the lid under hot water for a short time will often make it easier to open. Why?
To understand whether the hole in a thin, circular ring will get larger or smaller when heated in the oven, we can apply the concept of thermal expansion. When an object is heated, its molecules gain kinetic energy and vibrate more vigorously, causing them to move further apart. This expansion leads to an increase in the object's dimensions.
In the case of a thin circular ring, when it is heated, both its inner and outer circumference expand. However, the expansion is greater for the outer circumference, as it is farther from the center where the molecules experience less motion. As a result, the hole in the ring relative to its outer circumference becomes larger, indicating that the ring's hole will also get larger when heated in the oven.
Now, let's move on to the second question regarding the tight lid of a glass jar being easier to open after being exposed to hot water. This phenomenon occurs due to thermal expansion similarly.
When the glass jar and its lid are initially sealed, they are often maintained at room temperature. However, upon exposure to hot water, the lid expands more rapidly than the glass jar due to its smaller mass and material properties. As a result, the lid's diameter increases more than the diameter of the jar's opening.
This differential expansion creates a slightly looser fit between the lid and the jar, reducing the friction that holds the lid tightly in place. Consequently, the hot water effectively loosens the grip of the lid, making it easier to open.
In summary, both the thin circular ring's hole and the tight glass jar lid become larger when exposed to heat due to the concept of thermal expansion.