1. The problem statement, all variables and given/known data I've been working my way through the following question but I am a little bit stuck at this part: A gearbox and flywheel are as shown in FIGURE 4. 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 50 kg, a diameter of 1.5 m and is to accelerate from rest to 300 revs min–1 in 1 minute: Calculate the magnitude and direction of the torque required to hold the gearbox stationary (holding torque Th). 2. Relevant equations Input shaft rotating clockwise. Output shaft rotating anti-clockwise. Input Angular Velocity W1 = 0 RAD/s Final Angular Velocity W2 = (300*2π)/60 Final Angular Velocity W2 = 31.42 RAD/s Angular Acceleration α = (W2 - W1)/t Angular Acceleration α = (31.42 - 0)/60 Angular Acceleration α = 0.52 RAD/s Moment of inertia for solid disc I = 1/2*MR2 Moment of inertia for solid disc I = 0.5*50*0.752 Moment of inertia for solid disc I = 14.06 KG/m2 Torque of output shaft T2 = I*α Torque of output shaft T2 = 14.06*0.52 Torque of output shaft T2 = 7.3Nm Regarding gearbox efficiency T2 = (7.3/100)*92 Therefore T2 = 6.716Nm Torque of input shaft T1 = T2 * 5 Torque of input shaft T1 = 6.716 * 5 Torque of input shaft T1 = 33.58Nm 3. The attempt at a solution I'm struggling because a lot of the worked examples already have input or output power, which is what I need to calculate the holding torque TH. Could I calculate the output power using T2 * W2? Thus 6.716 * 31.42 = 211Kw and work backwards from there? Cheers!