Acar has a kinetic energy of 1.9 * 103 joules. if the velocity of the car is decreased by half, what is its kinetic energy?

Kinetic Energy = 1.9 * 10³

If velocity is decreased by half, kinetic energy will decrease by 4 times, so it would be:  1.9 * 10³ /4 = 0.475 * 10³ OR 475 Joules

So, your answer is 475 J

see earlier

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.