1. The problem statement, all variables and given/known data A rifle bullet leaves the muzzle of a gun at 800. m/sec. The rifle barrel is 80. cm long and the mass of the bullet is 20.g. What force was needed to accelerate the bullet? 2. Relevant equations Formulas: F(Total)= ma F= mg F = micrometers (m)(g) 3. The attempt at a solution t= 80 [itex]\div[/itex] 800 = .1s a= 800 - 0 [itex]\div[/itex] .1 = 8000 m/s^2 The answer is provided on my sheet as 8000 N, but I don't have a clue as to how to do that. Its the closest I've gotten to the answer.