Answer:
900 kg/m³
Explanation:
There are two forces on the object: weight and buoyancy.
Newton's second law:
∑F = ma
B − W = 0
B = W
Weight is mass times gravity:
W = m₀ g
Mass is density times volume:
W = ρ₀ V₀ g
Buoyancy force is equal to the weight of displaced fluid:
B = ρ V g
Therefore:
ρ V g = ρ₀ V₀ g
ρ V = ρ₀ V₀
ρ₀ = ρ V / V₀
One quarter of the object's volume is above the liquid, which means three quarters of its volume is below the surface.
Given that V = ¾ V₀ and ρ = 1200 kg/m³:
ρ₀ = 1200 (3/4)
ρ₀ = 900 kg/m³
