Hello, I really don't get something about work and I would like that someone help me, Please. ..
Well I have an exercise about two objects that are connected by an ideal rope that pass through a pulley that has a moment of inertia, so my problem is: when I use "energy" to get the velocity of the two objects, why it's not consider the work that the tension is doing. After all the tension is different by the two objects due the pulley and tensión is a non-conservative force...
2 answers
Actually, energy considerations will include the KE of the pulley. If you have different tensions on each side of the pulley, that is due to rope torque, and that torque is a force which produces KE on the PUlley. Your last sentence is correct.
well, sure the tension does work, but the idea is that you do not have to get into the innards of this system because its kinetic energy is described by the (1/2)(m1+m1)v^2 and (1/2) I omega^2 and its potential energy by the m g h of the two objects. You could solve the whole mess using the tensions on the two masses (the difference is accelerating the wheel) but luckily you do not have to do that. If a spring constant were given for the cord, well that would be a whole new ball game because it would store potential energy.