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Question
The figure below shows the use of a lever.
- State the principle of moments as applied to the above lever.
- To which class of lever does it belong ? Give an example of this class of lever.
- If FA = 10 cm, AB = 490 cm calculate:
- the mechanical advantage and
- the minimum effort required to lift the load (= 50 N).
Solution
(a) The principle of moments states that
Effort × AF = Load (50 N) × BF
(b) Effort is in between F and L.
∴ It belongs to the class III lever.
A class III lever is tongs or plucker
(c) Here, Effort arm FA = 10 cm
Load arm BF = 490 + 10 cm = 500 cm
∴ M.A. = `"Effort arm"/"Load arm"`
= `10/500 = 1/50`
Also, Effort × Effort arm AF = Load × Load arm BF
E × 10 = 50 × 500
∴ E = `(50 xx 500)/10`
= 2500 N
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