A0.050 kilogram bullet is fired from a 4.0 kilogram rifle which is initially at
rest. if the bullet leaves the rifle with a momentum of 20 kilogram-meters
per second, the rifle will recoil with a momentum of
(1) 1600 kg-m/s
(3) 20 kg-m/s
(2) 80 kg-m/s
(4) 0.25 kg-m/s

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s

firearm identification is the process of analyzing the bullets and cartridge cases left at a crime scene to determine if they came from a particular firearm. marks on the bullets and cartridges may be common to every firearm of that type. these are called class characteristics.