Answer to Question #316522 in Physics for PrE

Question

A block system of tire pullings has an efficiency of 70%.Calculate, the effort that will be required to raise a load of 42.00N

Answer 1

The effort that will be required to raise a load 

$$F=\frac{42.00\:\rm N\times 70\%}{100\%}=29.40\:\rm N$$