Question

A block and tackle system of pulleys consisting of 4 pulleys is used to raise a load of 50N through a height of 20m
If the total workdone against friction in the pulleys is equivalent to 800j
Calculate
I.Total workdone by the effort
ii.The efficiency of the system
iii.The effort applied.

Answer 1

I. (m * g * h) + 800 j

ii. (m * g * h) / [(m * g * h) + 800 j]

iii. (m * g) / {(m * g * h) / [(m * g * h) + 800 j]}

Answer 2

How?