A cyclindrical roller made of iron is 1.2 m lon g. Its internal radius is 24 cm and thickness of the iron sheet used in making the roller is 15 cm. What is the mass ( in kg) of the roller, if 1 cm3 of iron has 8g mass?
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Correct answer: D
Explanation
The correct answer is option 4 i.e. 907.2 π
Inner radius = 24 cm.
Outer radius = 24 + 15 = 39 cm.
The volume of the roller = π(R2 - r2)h
π(392 - 242) × 120 = π(63 × 15) × 120 = 113400π.
Mass of the roller in kg = (113400 × 8)/1000 = 907.2π