A toy gun uses a spring to project a 4.8 g soft rubber sphere horizontally. The spring constant is 12.0 N/m, the barrel of the gun is 14.3 cm long, and a constant frictional force of 0.028 N exists between barrel and projectile. With what speed does the projectile leave the barrel if the spring was compressed 6.5 cm for this launch? the answer is 2.98 m/s i was wondering if there is an easier way to solve this equation? i did this the first time and got 3.02 m/s but forgot how i did it. the second time i did it i used this formula V_f = sqrtKX_i^2 - 2fL/m V_f= sqrt ((12)(.065)^2 - 2(.028)(.143)/(4.8 x 10^-3)) = 2.98 I was wonder if anyone can tell me is there an easier way to doing this in a simple way. I know there is one which gave me the answer 3.02 i just forgot to write it down and forgot it just now.