A solid copper sphere of radius 9 cm is drawn into a wire of radius 4 mm. Find the length of the wire.
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Correct answer: A
Explanation
The correct answer is option 1 i.e. 60.75 m.
Volume of sphere = (4/3)πR3 = (4/3) × π × (9)3 = 972π cm2
Radius of the wire (r) = 4 mm = 0.4 cm
Let the length of the wire = h cm
Volume of cylinder = πr2h = π × (0.4)2 × h = 0.16πh cm3
So, 0.16πh = 972π
⇒ h = 972/0.16 = 6075 cm = 60.75 m