Question

By lubricating the pulley, the work needed was decreased from 50 J down to

44 J. The output work of the pulley remained 40 J.
The efficiency of the pulley AFTER lubrication is

Answer 1

Before lubrication:

`\tt (40)/(50)* 100\%=80\%`

The efficiency of the pulley after lubrication becomes:

`\tt (40)/(44)* 100\%=91\%`