force (S.E./P.D.F.). This is usually around 1 ftlb/lbf but can reach 1.4 ftlb/lbf.

The efficiency of bows also varies. Normally between 70 and 85% of the stored energy is transferred to the arrow. This stored energy is referred to as potential energy. When transferred to the arrow it is referred to as kinetic energy. The product of S.E./P.D.F. and efficiency can be called the power factor. There are two measurement standards of this quantity - ATA and IBO