Rotational Mechanics: Tension Difference in Pulley Due to Friction

AI Thread Summary
Tension differs on both sides of a pulley due to friction, which affects the net torque. The tension from one rope attempts to rotate the pulley in one direction, while the other rope's tension works in the opposite direction. For the pulley to rotate at a constant speed, the net torque must be zero, meaning the torque difference from the two tensions must counteract the frictional torque. Friction is applied at the pulley shaft, opposing its rotation, leading to a non-zero tension difference in the ropes. Understanding this relationship clarifies why tensions cannot be equal when friction is present.
shashank
Messages
3
Reaction score
0
I can't get it why tension is different in both sides of pulley due to friction?
 
Last edited by a moderator:
Physics news on Phys.org
The tension in the rope on one side of the pulley is trying to rotate the pulley in one direction, and the tension on the other side is trying to rotate the pulley in the opposite direction. If the pulley is rotating at a constant speed, then the net torque on the pulley has to be zero, which means that the difference between the torques from the two ropes has to exactly cancel the torque from friction. The frictional torque is non-zero, so the difference in the tension of the ropes has to be non-zero, which means that it can't be the same in both ropes.
 
  • Like
Likes AdityaDev and shashank
But I can't get that where is the friction being applied and in which direction?
 
Friction is being applied at the shaft of the pulley and opposes its rotation.
 
  • Like
Likes shashank
Thanks a lot sir...
 
The rope is tied into the person (the load of 200 pounds) and the rope goes up from the person to a fixed pulley and back down to his hands. He hauls the rope to suspend himself in the air. What is the mechanical advantage of the system? The person will indeed only have to lift half of his body weight (roughly 100 pounds) because he now lessened the load by that same amount. This APPEARS to be a 2:1 because he can hold himself with half the force, but my question is: is that mechanical...
Hello everyone, Consider the problem in which a car is told to travel at 30 km/h for L kilometers and then at 60 km/h for another L kilometers. Next, you are asked to determine the average speed. My question is: although we know that the average speed in this case is the harmonic mean of the two speeds, is it also possible to state that the average speed over this 2L-kilometer stretch can be obtained as a weighted average of the two speeds? Best regards, DaTario
Some physics textbook writer told me that Newton's first law applies only on bodies that feel no interactions at all. He said that if a body is on rest or moves in constant velocity, there is no external force acting on it. But I have heard another form of the law that says the net force acting on a body must be zero. This means there is interactions involved after all. So which one is correct?
Back
Top