Q6 of 52 Page 160

The diameter and thickness of a hollow metals sphere are 12 cm and 0.01 m respectively. The density of the metal is 8.88 gm per cm3. Find the outer surface area and mass of the sphere.

Thickness of sphere, t = 0.01m = 1 cm


Diameter of sphere = 12 cm


⇒ Outer Radius of sphere, RO = 6 cm


⇒ Inner Radius of sphere, RI = RO – t = 6 – 1 = 5 cm


Outer Surface area of sphere, A = 4πRO2


⇒ A = 4× 3.14 × 62


⇒ A = 452.16 sq.cm





⇒ V = 381.33 cm3



⇒ Mass = 8.88 × 381.33


⇒ Mass = 3385.94 gm


∴ Outer surface area and mass of the sphere is 452.16 sq.cm and 3385.94 gm


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