The volume of a cast-iron weight weighing 500 g is equal to 80 cm3. Is there a cavity inside the weight?

Data: V – the volume of the cast iron weight taken (V = 80 cm3; in the SI system V = 8 * 10 ^ -5 m3); mchg is the mass of the cast iron weight (mchg = 500 g; in the SI system mchg = 0.5 kg).

Const: ρh – density of cast iron (ρh = 7000 kg / m3).

If there is no cavity inside the cast iron weight taken, then the equality will be fulfilled: ρch = ρg.

ρh = mchg / V.

7000 = 0.5 / (8 * 10 ^ -5).

7000 kg / m3 ≠ 6250 kg / m3 (wrong).

Answer: There is a cavity inside the cast iron weight taken.