Question

In fig below shows the use of a lever.

(a) State the principle of moments as applied to the above lever.

(b) To which class of lever does it belong? Give an example of this class of lever.

(c) If FA = 10 cm , AB= 490 cm, calculate : (i) the mechanical advantage, and (ii) the minimum effort required to lift the load (= 50 N).

Answer 1

(a) The principle of moments: Moment of the load about the fulcrum=moment of the effort about the fulcrum
FB × Load = FA × Effort

(b) class 3 lever has the effort in the middle, the fulcrum at one end and the load at the other. Sugar tongs the example of this class of lever.

(c) Given: FA = 10 cm, AB = 490 cm, BF = 490 + 10 = 500 cm

Effort $=\frac{Load}{MA}=\frac{50}{0.02}=2500N$