Physics

A knowledge of basic physics helps to understand how a severe blow to an animal’s skull will induce immediate unconsciousness. During stunning there is a transfer of kinetic energy (the energy of movement) from the travelling object, i.e. the captive-bolt, to the animal’s head and from there directly to its brain.

Effective percussive stunning is achieved by delivering the maximum amount of energy to the correct part of the animal’s brain in the shortest possible time.

Kinetic energy (KE) is proportional to the mass (m) of the bolt and its velocity (v). this relationship is expressed by the following formula:

KE = ½mv²

An example of the above relationship is shown in Table 1. Kinetic energy is expressed in joules (J), mass is expressed in grams (g) and velocity in metres per second (ms¯¹). In this example the mass of the bolt is 150g and the amount of energy required for an effective stun is 130J.

It is the velocity of a moving object, rather than the mass, which has the greatest effect on its kinetic energy. If the velocity of the bolt is reduced, its ability to stun an animal effectively will be impaired. Regular and thorough cleaning of captive-bolt equipment is of paramount importance (see pages on Maintenance and Troubleshooting).