Question

A 6m crowbar is used to lift 500 N load up to 4 m height hanging at one end of it by pressing

the bar with 400 N effort up to the depth of 6 m at the other end, then calculate
(1) Input work.
(ii) Output work, and
(ii) Efficiency of the machine​

Answer 1

Work = force • distance

so (input) 400 • 6 = 2400 joules.

and (output) 500 • 4 = 2000 joules

and efficiency = output energy ÷ input energy

so 2000 ÷ 2400 = 83%

input energy = 2400 joules

output energy = 2000 joules

efficiency = 83%