Estimate mass using density and sphere volume formula

Steps:

• Radius = diameter/2 = 20 cm / 2 = 10 cm = 0.1 m.
• Volume V = (4/3)πr³ ≈ (4/3)(3.14)(0.1)^3 ≈ 0.0042 m³.
• Density of copper ≈ 8900 kg/m³.
• Mass = density × volume ≈ 8900 × 0.0042 ≈ 37 kg.

Why B is correct:

• Calculated mass of 37 kg is a reasonable order-of-magnitude estimate matching 10 kg, using the formula mass = density × volume.

Why the others are wrong:

• A: 0.1 kg is too low, like the mass of a small apple, not a 20-cm copper sphere.
• C: 1000 kg is too high, equivalent to over 1 metric ton, far exceeding the calculated value.
• D: 10000 kg is excessively high, like a large vehicle's mass, unrealistic for this size.

Final answer: B