text: 750rpm is 25*pi radians per second and the disc slows down from this to 0 in 10 seconds - you can work out what the acceleration was and whether it is -ve or +ve\n\nSomewhere you probably have a table showing moments of inertia of common symmetrical shapes. If not you can find one here -\nhttp://eta.physics.uoguelph.ca/tutorials/torque/Q.torque.inertia.html\n\nFind the formula for a disc or cylinder rotating about the axis. This gives you I. (convert cms to metres when you work out I to be sure you will get torque in N.m at the end).\n\nnow you find the torque using w_final = w_initial + torque*I\n\ngood luck