# ballistic coefficient

The ballistic coefficient is a measure of a projectile's ability to coast. It is defined as *C*_{b} = *M*/*C*_{d }*A* where *M* is the projectile's
mass and *C*_{d}* A* is the drag
form factor. At any given velocity and air density, the deceleration
of a rocket from drag is inversely proportional
to this value. Intuitively, it is the principle behind why a tightly crumpled
piece of paper can be thrown farther than a loosely crumpled one.