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...
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.
Hello! I'd be happy to help explain the concept you're struggling with.
In the scenario you described, where two objects are connected by an ideal rope passing through a pulley, it is true that the tension in the rope is different for each object due to the presence of the pulley. The tension is exerted by the rope to keep both objects moving together.
When using the concept of energy to analyze the motion of the objects, we can make use of the principle of conservation of mechanical energy. This principle states that the total mechanical energy of a system remains constant as long as no external forces do work on the system.
In this case, the tension in the rope, although it may vary for each object, is considered an internal force in the system. This means that the tension does not do any net work on the system as a whole. The reason for this is that for every increment of work done by the tension on one object, an equal and opposite increment of work is done by the tension on the other object.
Essentially, the tension forces cancel each other out in terms of net work done on the system. Therefore, we do not need to consider the work done by tension when using energy concepts to determine the velocities of the objects.
It's important to note that this approach assumes there are no other external forces (such as gravity or friction) acting on the objects. If there are additional external forces, they would need to be taken into account when analyzing the motion.
I hope this explanation clarifies the concept for you! Let me know if you have any further questions.