How to calculate the change of mass?

Finding mass Fq = mg -1.985 = -9.782m 0.202924 = m 0.203 = m - 1.985 m -9.782 Find initial momentum Find final momentum| Find change of momentum P = my Pfinal = 0.203(0.128) Pfinal - Pinitial = 0. 026 - (-0.061) P = 0.203(-0.301) = 0.025984 PA = 0.087 P = -0.061 = 0.026 Percentage error Percentage error = Jestimated number - actual number | x 100 actual number = 10.087-0.0621. x 100 0.062 = 0.025 x 100 0.062 = 0.403 x 100 = 40.3 Percentage error = 40.3% Find change of velocity AV = Vfinal - V initial AV = 0.128-(-0.302) Av = 0.43