When a flat piece of metal with a hole in it is heated, the size of the hole will generally increase. This phenomenon occurs due to the expansion of the metal in all directions when it is subjected to heat.
When the metal is heated, the increase in temperature causes the atoms and molecules within the metal to vibrate more vigorously, which increases their average kinetic energy. This increase in kinetic energy leads to an expansion of the metal in all directions. As a result, the dimensions of the metal, including the diameter of the hole, tend to increase.
To understand this, consider the behavior of the metal atoms surrounding the hole. As they gain energy from the heat, they move more freely and occupy a larger volume. Since the metal expands uniformly in all directions, the metal around the hole expands outward, causing the hole itself to enlarge.
It's important to note that the amount of expansion and the extent to which the hole increases in size depend on various factors, such as the type of metal, its coefficient of thermal expansion, and the specific conditions of the heating process. Different metals have different coefficients of thermal expansion, which determine how much they expand or contract for a given change in temperature.
In summary, when a flat piece of metal with a hole is heated, the hole typically increases in size because the metal expands uniformly in all directions due to increased molecular motion.