1. The problem statement, all variables and given/known data A flywheel is attached on the output of the gearbox. The output shaft rotates in the opposite direction to the input shaft at 5 times its speed. The gearbox has an efficiency of 92%. If the flywheel is solid, has a mass of 50kg, a diameter of 1.5m and is to accelerate from rest to 300 revs min-1 in 1min: a) Calculate the torque required at input T1. b) Calculate the magnitude and direction of the torque required to hold the gearbox stationary (holing torque Th). Show the direction of the holding torque applied to the shaft with the aid of a sketch. c) Plot a graph of the input power against time when taking the flywheel from rest to 300 revs min-1. 2. Relevant equations α=(ω2-ω1)/t T=I*α I=0.5*m*r2 η=(-To*ωo)/(Ti*ωi) 3. The attempt at a solution a) ωi=-0.2ωo ω2=300 revs min-1=300*(2π/60)=10π rads-1 ωo=-10π rads-1 α=(ω2-ω1)/t=(10π-0)/60=π/6 rads-2 I=0.5*m*r2=0.5*50*0.752=14.062 kgm2 To=I*α=14.062*(π/6)=7.3628 Nm ωi=-0.2*-10π=2π rads-1 η=(-To*ωo)/(Ti*ωi) η(Ti*ωi)=-To*ωo Ti*ωi=(-To*ωo)/η Ti=(-To*ωo)/(η*ωi)=(-7.3628*-10π)/(0.92*2π)=36.814/0.92=40.0152 Nm b) Ti+To+Th=0 Th=-Ti-To=-40.0152-7.3628=-47.378 Nm As the holding torque Th has a negative sign the direction of it is clockwise which is opposite direction to the Ti and To. The a) and b) seem to be not too difficult (if I got it right), however after spending several hours I can't workout c). Can someone put me in the right direction. I hope a) and b) are correct.