When a certain weight is suspended from a long uniform wire, its … - Vidyadip

MCQ

When a certain weight is suspended from a long uniform wire, its length increases by one $cm$. If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one then the increase in length will be

A
$0.5 cm$
B
$2 cm$
✓
$4 cm$
D
$8 cm$

✓

Answer

Correct option: C.

$4 cm$

(c)
$l=\frac{F L}{A Y}$
$ \Rightarrow l \propto \frac{1}{r^2}(F, L \text { and } Y \text { are constant })$
$\frac{l_2}{l_1}=\left(\frac{r_1}{r_2}\right)^2=(2)^2=4 \Rightarrow l_2=4 l_1=4 \mathrm{~cm}$

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