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Volumes Practice Test 1

Question : 9 of 40

Marks: +1, -0

Solution: 👈: Video Solution

Concept:

When a solid is reshaped, its volume remains constant.

Explanation:

Radius of copper rod

= \frac{1}{2}

cm.

Length of rod

= 8

cm.

Length of wire

= 18

= 1800

cm.

Let radius of wire be

r

By volume conservation,

\pi \left(\frac{1}{2}\right)^2 \times 8 = \pi r^2 \times 1800

\pi \times \frac{1}{4} \times 8 = 1800\pi r^2

2\pi = 1800\pi r^2

r^2 = \frac{2}{1800} = \frac{1}{900}

r = \frac{1}{30} \text{ cm}

Answer:

The radius of the wire is

\frac{1}{30}

cm, so the correct option is D.

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