(b) On what factor does the mechanical advantage of a simple machine depend? (a) N/m B. Very short answer questions, 1. What is the principle of simple machine? 2. 3. The efficiency of simple machine is 75%. What does it mean? 4. S. What is lever? In how many classes is lever classified? Write the name of a simple machine used to change the direction of force. 6.the velocity ratio of a pulley system is 4.what does it mean? 0 Reliant Science - 9​