Work Input vs Work Output in Pulley Systems

[moomoocow]

hello again,
i know that in an ideal pulley system, work input is equal to work output..however in reality, that is not possible due to friction

but what confuses me is that within what percentage is work input=work output?
how are we supposed to find the percentage?

thank you!

 

[OlderDan]

In a real pulley, the friction results in a torque that opposes the rotation of the pulley. If you know the torque and the angular displacement you can calculate the work done by friction. The work output is the work input minus the work done by friction.