Which of the following describes the energy transfer in firing a firearm?

• A. The firing pin strikes the primer, igniting the gunpowder, producing gas that drives the projectile
• B. The projectile leaps from the barrel by wind power
• C. The safety switches on to release the cartridge
• D. The shooter manually pushes the projectile

Answer: (A)

Energy transfer in firing a firearm begins with chemical energy stored in the propellant. When the firing pin strikes the primer, the primer detonates and lights the gunpowder, causing rapid combustion. The fast-burning powder creates a high-pressure gas that expands behind the bullet and pushes it forward, accelerating it down the barrel. In this process, chemical energy is converted into the kinetic energy of the bullet (and some energy lost as heat and sound). The recoil you feel comes from the momentum of the expanding gas and bullet as the system responds.

The other ideas don’t fit this mechanism: wind power can’t provide the controlled, internal energy needed to propel a bullet, a safety switch isn’t what releases the cartridge, and a shooter pushing the projectile manually isn’t how firearms operate or generate the required energy.