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ICSE Class 10 Physics Question 3 of 19

Machines — Question 6

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Question 6

A pair of scissors is used to cut a piece of cloth by keeping it at a distance of 8.0 cm from its rivet and applying an effort of 10 kgf by fingers at a distance 2.0 cm from the rivet.

(a) Find: (i) the mechanical advantage of scissors and (ii) the load offered by the cloth.

(b) How does the pair of scissors act - as a force multiplier or as a speed multiplier?

Answer

(a)

(i) We know that,

Mechanical advantage M.A.=Effort armLoad arm\text{Mechanical advantage M.A.} = \dfrac{\text{Effort arm}}{\text{Load arm}} \\[0.5em]

Given,

Load arm = 8.0 cm

Effort arm = 2 cm

Substituting the values in the formula we get,

M.A.=28⇒M.A.=0.25M.A. = \dfrac{2}{8} \\[0.5em] \Rightarrow M.A. = 0.25 \\[0.5em]

(ii) We know,

Load=M.A.×EffortLoad = M.A. \times Effort \\[0.5em]

Given,

Effort = 10 kgf

Substituting the values in the formula we get,

Load=0.25×10⇒Load=2.5kgfLoad = 0.25 \times 10 \\[0.5em] \Rightarrow Load = 2.5 kgf \\[0.5em]

(b) As the mechanical advantage is less than 1 i.e. M.A. < 1. Hence, the pair of scissors acts as a speed multiplier as there is larger displacement of load than displacement of effort.