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A solid sphere of radius 3 cm is melted to form a hollow right circular cylindrical tube of length 4 cm and external radius 5 cm. The thickness of the tube is
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- 1 cm.
- 9 cm.
- 0.6 cm.
- 1.5 cm.
- 1 cm.
Correct Option: A
| Volume of solid sphere = | π(3)³ | |
| 3 |
= 36π cu. cm.
Volume of the metal of tube = π(R² – r²)h cu. cm.
where R = 5 cm. r = in-radius
∴ π(R² – r²) h = 36π
⇒ (25 – r²) × 4 = 36
| ⇒ 25 – r² = | = 9 | |
| 4 |
⇒ r² = 25 – 9 = 16
⇒ r = 16 = 4 cm.
7there4; Thickness of tube = 5 – 4 = 1 cm.
