A two cylinder engine with cranks at right angles developes 75 KW at mean speed 400 rev/min.the coefficient of speed fluctuation should be more than 0.003.the mean diameter of the flywheel is 1.2 m.the maximum variation of energy per revolution is found to be 20%of the mean energy. as found from a dynamic analysis of the actual forces in the engine. If the arms and hub contribute 5% of the flywheel effect (K=0.95), what is the necessary dimensions of a square rim section of cast iron which has density of 7000 kg/meter cube.