Question

A hollow spherical shell is made of a metal of density 4.5g per cm³. If its internal and external radii are 8cm and 9cm respectively, find the weight of the shells.

Answer 1

I hope this helps you.

Answer 2

Here's the answer :)

Let the internal radius of hollow spherical shell be r1 = 8 cm

and the external radius of hollow spherical shell be r2 = 9 cm

Thus,

The volume of spherical shell (V)
$\sf{ = \frac{4}{3}\pi({(r1)} {}^{3} + (r2) {}^{3} )}$

Thus,
$\sf{V = \frac{4}{3} \times \frac{22}{7} \times ( {9}^{ 3} - 8 {}^{3}} )$

$\sf{ = \frac{88}{21} \times (729 - 512)}$

$\sf {= \frac{88}{21} \times 217}$

$\sf{ = 88 \times 10.33}$

$\sf{ = 909.33} \: cm {}^{3}$


Now,

Weight of 1 cubic cm = 4.5 gm

Thus,

The weight of the spherical shell

= 4.5 × 909.33

= 4091.98

= 4092 grams ( approx )

= 4.902 kg

Thus,

Weight of the shell is 4.902 kg.

______________________________

Thanks!!