## Trajectory

Updated Media sources (1) Print Topic Share Topic
views updated

views updated

# Trajectory

The trajectory of a bullet is the path of flight it follows from being fired to reaching its target. In cases of shootings that claim a victim as their target, the forensic specialist will want to try to work out the trajectory of the bullet as part of the crime scene reconstruction . The science of investigating projectile motion is known as ballistics and involves equations that can be used to work out a trajectory.

When the trigger of a gun is pulled, it sets off an explosion in the shell of the bullet. Chemical energy is converted into kinetic energy, and the bullet leaves the gun at a high velocity. At this point it is subject to the forces of gravity and air resistance, which make it travel in a roughly parabolic path. The range of the trajectory is the total distance the bullet travels in a horizontal direction, that is, the distance between the gun and its target.

When analyzing the trajectory of a bullet, ballistics investigators divide it up into three parts. First, there is the short journey the bullet makes from where the firing pin strikes it to the point where it leaves the gun. Then there is the journey it makes towards its target, which may last anything from a fraction of a second to several seconds. Finally, the bullet gives up its kinetic energy as it travels through its target. The bullet may end up lodged in a victim's body or, if it has sufficient kinetic energy, it may emerge on the other side, creating an exit wound as well as an entry wound. Sometimes a bullet will ricochet, that is, deviate from its trajectory because of an impact with an object. It can still hit someone but the shot would not have been aimed directly at the victim, which may be an important piece of evidence .

The main task of the ballistics specialist is to work out the range of a bullet's trajectory. When a bullet leaves a gun, it carries various gases with it that often form a tattoo-like pattern on the victim's skin. The extent and spread of this pattern is often revealing about the range between the perpetrator and the victim. The investigator will often try to reproduce the pattern by firing the weapon, if it is available, or a similar one at blank targets in a laboratory situation. Knowing the range can help establish where a perpetrator was standing and may either contradict or corroborate witness statements. The range can also help determine whether a fatal shooting was homicide or suicide.