Multiple choice

Find the mass of $200$ steel spherical ball bearings, each of which has radius $0.7cm$, given that the density of steel is $7.95g/{cm}^{3}$. (Mass $=$ Volume $\times$ Density)

  1. $2.29Kg$
  2. $2.9Kg$
  3. $3.29Kg$

  4. None of these
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A Correct answer
Explanation

Volume of one sphere = (4/3) * pi * r^3 = (4/3) * 3.14159 * (0.7)^3 = 1.4367 cm^3. Mass of 200 spheres = 200 * 1.4367 * 7.95 = 2284.4 g = 2.284 kg, which rounds to 2.29 kg.

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