The Science of Projectiles
Forensic ballistics applies the physics of projectile motion to criminal investigation. When a bullet is fired, it follows a trajectory governed by its initial velocity and angle, modified by gravity, air resistance, and environmental conditions. By analyzing bullet holes, impact craters, and recovered projectiles, forensic examiners can reconstruct the shooter's position, the weapon type, and the sequence of events at a crime scene.
External Ballistics
Once a bullet leaves the barrel, it is subject to gravity (pulling it down), aerodynamic drag (slowing it), and spin from rifling (stabilizing it gyroscopically). The trajectory is a curved path — not a straight line — that drops increasingly with distance. A 9mm pistol bullet drops about 35 cm at 100 m; a rifle bullet at 800 m/s drops only 8 cm at the same distance but over 3 m at 500 m. These differences are critical for crime scene reconstruction.
Terminal Ballistics
The bullet's condition at impact — its velocity, energy, and deformation — provides forensic evidence. Kinetic energy determines penetration depth and wound characteristics. Hollow-point bullets expand on impact, transferring energy rapidly; full-metal-jacket rounds may pass through, creating both entry and exit wounds. The bullet mass and impact velocity together determine the energy available, following E = mv²/2.
Reconstruction in Practice
This simulation models a bullet's flight from muzzle to impact, accounting for gravity and aerodynamic drag. By adjusting muzzle velocity, launch angle, bullet mass, and drag coefficient, you can match real-world scenarios: from a 9mm pistol shot across a room to a rifle engagement at hundreds of meters. The computed drop, velocity retention, and energy help forensic analysts verify or refute witness accounts and suspect statements.