A force of 11n is applied to the handle of a screw driver being used to pry off the lid of a paint can. what is the efficency of the screw driver.

Efficiency of a machine = output energy / input energy

first solve the input energy = Fd

where f is the force applied

d is the distance

Input = 11 N (0.3 m) = 3.3 J

output = 3 J

efficiency = 3 / 3.3 = 0.91

efficiency = 91 %