A crowbar is used as a lever. The effort force of 40 newtons moves 3 meters. The resistance force of 54 newtons moves 2 meters. What is the efficiency of the lever?
A) 100% because energy must be conserved
B) 90%
C) 25%
D) 18%
i need help. i don't know how to figure this one out
Output work = 108 J.
Input work = 120 J
Efficiency = 108/120 = 9/10 = 90%
(Energy can be converted to heat in friction at the fulcrum, or useless potential energy distorting the crowbar)