Let’s assume that the ball is solid, with no voids inside. If the density of copper is ρ = 8900 kg / m³, then the mass of the ball m, kg, will be equal to
m = ρ * V = 8900 * (120 * 10 ^ (- 6)) = 1.068 kg.
The weight of the ball P, H, is determined by the formula
P = m * g,
where g = 9.81 m / s² is the acceleration of gravity at the Earth’s surface.
P = 1.068 * 9.81 = 10.5 N.
But according to the condition, the ball weighs only 8.5 N, so it cannot be solid, which means it has emptiness inside.
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