A sphere of radius 7 cm is melted and drawn into a wire of radius 0.21 cm. The length of the wire is (approximately) -
Answer & explanation
Correct answer: option 2
Volume of sphere = volume of cylinder (wire)
\(\frac{4}{3}\) \(\pi \) r3 = \(\pi \)r2h
⇒ \(\frac{4}{3}\) (7)3 =(0.21) (0.21) × h
⇒ h = \(\frac{4\;×\;7\;×\;7\;×\;7}{3\;×\;21\;×\;21}\) × 104
Length of wire (h) = 9.33 × 104 cm