Determine the volume of the cavity of a steel ball with a mass of 3.9 kg, if its volume is 550 cm3.

m = 3.9 kg.

V = 550 cm3 = 0.00055 m3.

ρ -?

The density of a substance ρ is called a scalar physical quantity, which is determined by the ratio of the mass of a substance m to the volume V it occupies: ρ = m / V.

Physical meaning: the density of the substance ρ shows what mass the substance has, taken V = 1 m3.

ρ = 3.9 kg / 0.00055 m3 = 7090.9 kg / m3.

Steel, taken in a volume of V = 1 m3, will have a mass of m = 7090.9 kg.

Answer: the steel from which the ball is made has a density ρ = 7090.9 kg / m3.