1. A Flywheel (A) mass 100kg and radius of gyration 1200mm rotates 150rpm clockwise. The knetic energy of this flywheel is to be reduced 20% by impacting a second flywheel B rotating at 80 rpm in opposite direction, such that they have the same clockwise angular velocity after inpact. A) calclate mass of flywheel B if its radius of gyration is 800mm, B. calculate energey lost to the surroundings, C. is the impact elastic, give reasons 2. KE = 0.5 x I x W^2, I = M x K^2, 3. K = 1.2m W = 150 rpm = 15.7 r/s M = 100kg I = MxK^2, I = 100 x 1.2^2 , I = 144 Flywheel A KE = 0.5 x I x W^2 =0.5 x 144 x 15.7^2 = 17747.28 = 17.75J -20% = 17.75 = 14.2 J Energy lost = 3.55J, this is acquired by Flywheel B Flywheel B 80rpm = 8.4 r/s KE = 0.5 IW^2 I = KE x 2 / w^2 I = 3550 x 2 / 8.4^2 = 100.62 Kgm^2 Mass, I = M x K^2 M = I / K^2 = 100.62 / 0.8^2 =157.2kg (Check – I = K^2M, 0.8^2 x 157.2 = 100.6) B). Energy lost to the surroundings Kinetic Energy before impact 17.75J – Kinetic Energy after impact 14.2J 17.75 – 14.2 = 3.55J C). No it is inelastic as energy is given up and the 2 bodies move in the same direction at the same speed.