I am trying to determine the velocity of a ball fired horizontally from ballistic pendulum. The data is as follows: ball mass: 62.2 g spring mass: 14.7 g rod mass: 89.3 g length of spring: 126.1 mm initial spring length: 5 cm compressed spring length: 1 cm k: 2.05 N/m calculated from previous experiment Using the Work-Kinetic Energy Theorem Kbo + Kro + Kso = Kb + Kr + Ks .5mv^2oball + .5mv^2orod + .5kx^2 = .5mv^2ball + .5mv^2rod - .5kx^2 I took all the terms to 0 and got v_oball = (kx^2 /m_ball)^.5. this doesn't seem correct, shouldn't the mass and lengths of the spring and rod be used? 2nd part is to determine the range it should travel from a height of 101.05 cm above ground fired horizontally. I used the R = v^2 /g sin2t but since angle t= 0 I am getting 0 for the range.