A solid lead ball of radius 6 cm is melted and then drawn into a wire of diameter 0.2 cm.

Question:

A solid lead ball of radius 6 cm is melted and then drawn into a wire of diameter 0.2 cm. The length of wire is
(a) 272 m
(b) 288 m
(c) 292 m
(d) 296 m

Solution:

(b)  288 m

Let h m be the length of wire.
Volume of the lead ball = volume of the wire

$\Rightarrow \frac{4}{3} \pi \times 6^{3}=\pi \times(0.1)^{2} h$

$\Rightarrow h=\frac{4 \times 216}{3 \times 0.01}=28800 \mathrm{~cm}=288 \mathrm{~m}$

 

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