This is a virtual physics experiment from Virtual Science's Virtual Physics Laboratory. It allows you to calculate the velocity of a fired shell from an AK 47 using a ballistic balance. You fire a round into a suspended wooden block which then swings. You measure the horizontal displacement which allows you to calculate the height the block gains which is then used to calculate the gained potential energy, This can be equated to the kinetic energy on impact. Conservation of momentum is then used to get the velocity of the projectile. This is one of thirty experiments from the Virtual Physics Laboratory. This has gained the Association for Science Education's Green Tick of approval. More information at https://www.virtual-science.co.uk/ This is a free Physics resource which you are free to use in the classroom. If you need more comprehensive instructions then email me for them at rob@virtual-science.co.uk.