Calculate Force (N) on Bullet in 0.8m Rifle Barrel

[PepeF.]

a 5.3g bullet leaves the muzzle of a rifle with a speed of 618.9 m/s.

What constants force (N) is exerted on the bullet while it is traveling down the 0.8m lengh of the barrel of the riffle?

 

[Tzim]

What did you try to do?