Final answer:
The velocity due to the backward motion of a gun when a bullet is fired is known as recoil velocity. This phenomenon is an application of Newton's third law of motion and can be quantified using principles of conservation of momentum and mechanics.
Step-by-step explanation:
The velocity exerted due to the backward motion of the gun when a bullet is fired is commonly referred to as the recoil velocity. According to Newton's third law, for every action, there is an equal and opposite reaction. Therefore, when a gun pushes a bullet forward, the bullet pushes backward on the gun with equal force, causing the gun to move backward. This is similar to how car tires push backward on the road resulting in the road pushing the car forward, and a jumper pushing down on the ground results in the ground pushing the jumper upward.
In a recoilless rifle, the shell is not secured, allowing it to eject from the rear as the bullet is fired forward, thus reducing the recoil felt by the shooter. It's important to note that standing behind a recoilless rifle is unsafe due to the backward ejection of the shell.
Considering a professional application, the recoil velocity can be mathematically calculated using conservation of momentum. For example, if a 1.00-kg plunger recoils after interacting with a 0.0200-kg bullet fired at 600 m/s, the recoil velocity can be found, and the average force exerted upon it by the gun can also be calculated when it is stopped over a certain distance.