A solid sphere of radius 3 cm is melted to form a hollow cylindrical tube of length 4 cm and external radius 5 cm. The thickness of the tube is?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 1 cm
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Understanding |
Application |
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External radius of cylinder R = 5 cm Height of cylinder = 4 cm Radius of the sphere = R1 = 3 cm We know: Volume of Hollow cylinder = π(R2 – r2)h Volume of sphere = (4/3) πr3 |
According to the question: Volume of cylinder = volume of sphere π(R2 – r2)h = 4/3 × π(R1)3 ⇒ (52 – r2) × 4 = (4/3) × 3 × 3 × 3 ⇒ 25 – r2 = 9 ⇒ r2 = 25 – 9 = 16 ⇒ r = 4 cm So, Thickness of cylinder = 5 – 4 = 1 cm |