Question

find the weight of a hollow sphere of metal having internal and external diameters as 20 cm and 22cm respectively if 1cm3 of metal weighs 21 g.

Answer 1

Answer:

Step-by-step explanation in the pic attached

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Answer 2

Answer:

29127.9996 g

Step-by-step explanation:

Inner diameter = 20 cm

Inner radius = $\frac{20}{2}=10 cm$

Outer diameter = 22 cm

Outer radius = $\frac{22}{2}=11 cm$

Volume of hollow sphere = Outer volume - Inner volume

                                          =$\frac{4}{3} \pi (R^3-r^3)$

                                          =$\frac{4}{3} \times \frac{22}{7} (11^3-10^3)$

                                          =$1387.0476 cm^3$

1 cubic cm = 21 g

1387.0476 cubic cm = $1387.0476 \times 21 =29127.9996 g$

Hence the weight of a hollow sphere of metal is 29127.9996 g