In the United States, a "quarter" is a common informal term used to refer to a quarter of various units of measurement, such as a quarter of a dollar, a quarter of a year, or a quarter of other divisible quantities. However, when used in the context of weight or mass, a "quarter" typically refers to a quarter of a hundredweight (cwt).
Since a hundredweight (cwt) in the United States is equal to 100 pounds (lbs), a quarter of a hundredweight is equal to:
1 quarter (US) = 25 pounds (lbs)
So, when you see "quarter" used in the context of weight or mass in the United States, it generally means 25 pounds. This term is often used informally, especially in agricultural or trade contexts, to refer to a convenient fraction of weight.
A "slug," in the context of mass, is a unit of measurement primarily used in the United States customary and British imperial systems. It is not a widely used unit and is considered somewhat archaic. The slug is used to measure mass and is defined as the mass that accelerates at a rate of one foot per second squared (1 ft/s²) when a force of one pound-force (1 lbf) is applied to it. In other words, a slug is the mass that results in an acceleration of 1 ft/s² when a force of 1 lbf is applied to it.