1. The problem statement, all variables and given/known data This is a question that's supposed to prove to us that you can use the work-kinetic energy theorem as a second theory of motion. Except I keep getting different answers when I work it out first w/ KET and second with Newton's Laws. So I'm definitely NOT fulfilling the objective here... In a rifle barrel, a 15 g bullet is accelerated from rest to a speed of 780 m/s. a) Find KE, at rest AND when it reaches 780 m/s. b) Find work done. c) Barrel = 72 cm long. Find mag. of average net force with Fnet = W/delta'r'cos(theta), where delta'r'cos(theta) is the displacement. And then you find acceleration w/ Newton's Laws and the net force. 2. Relevant equations KE = 1/2mv^2, W = kf - ki, Fnet = ma 3. The attempt at a solution At initial position, KE = 0 At final speed, KE = 5.85 J Net force = 5.85 / (0.72m)(1) = 8.125 N (??) Constant acceleration. This is so wrong.... 422500 m/s^2 Using vf^2 = vi^2 + 2a(x) So my Fnet here = (0.015kg)(422500 m/s^2)... Thanks!