Question

Find the amount of water displaced by a solid spherical ball of diameter 4.2 cm, when it is
completely immersed in water.
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Answer 1

For the spherical ball;

diameter = 4.2 cm

radius = 4.2/2 = 2.1 cm

volume of water displaced = volume of the spherical ball

$\: \: \: \: vol(water \: displaced) \\ = \frac{4}{3} \pi \: {r}^{3} \\ = \frac{4}{3} \times \frac{22}{7} \times (2.1) \times (2.1) \times (2.1) \\ = \frac{4}{3} \times \frac{22}{7} \times \frac{21}{10} \times \frac{21}{10} \times \frac{21}{10} \\ = \frac{4}{3} \times 22 \times \frac{3}{10} \times \frac{21}{10} \times \frac{21}{10} \\ = 4 \times 22 \times \frac{1}{10} \times \frac{441}{100} \\ = \frac{441 \times 88}{1000} = \frac{38808}{1000} \\ = 38.808 \: {cm}^{3}$

now,

$\: \: \: 1000 {cm}^{3} = 1l \\ \: \: \: \: \: \: \: \: \: 1 \: {cm}^{3} = \frac{1}{1000} l = \: 1ml \\ 38.808 {cm}^{3} = 38.808 \: ml$

Hence, volume of water displaced by the spherical ball is 38.808 mL.