Striking velocity affects terminal performance of the bullet in several ways:striking velocity determines bullet energy on impactstriking energy varies directly with bullet weightstriking energy varies as the square of velocity. In other words, a change in bullet striking velocity will have a much greater effect on bullet striking energy than a proportional change in bullet weight. Doubling bullet weight doubles bullet striking energy, whereas doubling bullet striking velocity quadruples striking energy. Hollow-point bullets striking at velocities below their expansion threshold behave like full-metal-jacket bullets, i.e., they do not expand at all. Depictions on TV and in motion pictures that show bullet impact immediately knocking a character off his feet are unrealistic.