Crowbar

A crowbar is a lever made from a metal bar, usually with a single curved end and flattened points, used to force two objects apart or to gain mechanical advantage when lifting something heavy; the curved end typically carries a notch for pulling nails. The tool works as all three classes of lever depending on how it is used, with the curved end generally acting as a first class lever and the flat end as a second class lever, and a flat, straight-edged version is sometimes called a utility bar. The name comes from the bird, the crow, most likely because the tool's curved, split end resembles a crow's foot or beak; the earliest documented use of the word dates to around 1400, and William Shakespeare has a character call for an "iron crow" in Romeo and Juliet. Crowbars are typically forged from medium carbon steel, sometimes hardened at the working ends, and are commonly made from hexagonal or cylindrical steel stock, though some designs use a rounded, I-shaped shaft instead.