Question

A crowbar of length 100 cm is used to lift a load of 5 kgf. It has its fulcrum at a distance of 20 cm from the load. Calculate:
(i) the mechanical advantage of a crowbar and,
(ii) the effort applied at the other end.

Answer 1

Given: L = 5 kgf, Load arm = 20 cm, Effort arm = 100 – 20 = 80 cm.
(Since the crowbar is the lever of first order with the fulcrum in between the load and the effort).

(i) Mechanical advantage =`("Effort arm")/("Load arm")=80/20=4`

(ii) M.A. =`"Load(L)"/"Effort(E)"`

∴ Effort =`"Load(L)"/"M.A."=5/4`

= 1.25 kgf.