But that is why the question arises. Its is not like the flywheel can generate whatever torque I need it to . If i connect a rotating flywheel to a shaft with a gearing and wheel at the end I need to know how much torque does it apply so as to then know what is the power and angular accleration . Its not the otherway around . Even if torque is a function of alpha(angular acceleration) I can't find out the alpha of shaft connected without testing can I ? Thats is why I want to know whether there was any way to know without experimenting .