Machine Efficiency

Question

A force of 455 N is exerted in pulling 15 m of rope using a pulley system to lift a 935 N object 5 m. What is the efficiency of the system?

 

...What is the difference between Work in and Work out? How do I find out based on the question?

 

 

Answer 1

W_i = work in

W_o = work out

η = efficiency

 

W_i = (455 N)(15 m) = 6825 Nm

 

W_o = (935 N)(5 m) = 4675 Nm

 

η = W_o/W_i = 4675/6825 ≅ 0.685, which is 68.5%