calculate the efficiency of the following machines:?

Question

1. a lever is used to lift a 45 N rock. the applied force is 75 N.
2. a pulley system raises a 39 N log with an applied force of 45 N.
3. you do 425 J of work to push a 75 N box up a ramp until the box is 2.5 m above the ground

Answer 1

To calculate effciencey you need to use:
Eff = work out / work in

Answer 2

1. Efficiency = (work done by machine/ actual work done by machine) *100%= (45/75)*100= 60%

2) Efficiency= (39/45)*100% = 86.67%

3)Efficiency = (75*2.5/425)*100 = 44.12%