They are called short-period comets. short-period comets are thought to originate in the kuiper belt, which is a belt of icy objects just beyond the orbit of the planet

The Kuiper belt is a region between about 30 and 50 AU from the Sun in the plane of the ecliptic. It is believed to be where most of the trans-Neptunian objects are, including Pluto and several other recently discovered dwarf planets. It is also thought to be the origin of many of the solar system's short-period comets. There are several types of Kuiper belt objects, or KBOs. Classical KBOs orbit between 30 and 50 AU from the Sun with most between 42 and 48 AU.

Explanation:

in simple terms, the principle states that the buoyancy force on an object is equal to the weight of the fluid displaced by the object, or the density of the fluid multiplied by the submerged volume times the gravitational acceleration, g. this is also known as upthrust.