What is the mass of a bullet that takes 15 cm to decelerate from a muzzle velocity of 320 m/s to resting and the average force decelerating the bullet is 2013n?

given that bullet decelerate from muzzle velocity 320 m/s to rest in 15 cm distance

so here we know that

now we can use kinematics

now we know that force acting on the bullet is

now by formula of force

so mass of bullet is 5.90 g

he kicked it 10 feet straight up into the air? i think this works.