Answer:
0.8
Explanation:
Draw a free body diagram of the stone. There are 3 forces:
Weight force mg pulling down,
Buoyancy force ρVg pushing up,
and normal force N pushing up.
Sum of forces:
∑F = ma
N + ρVg − mg = 0
ρVg = mg − N
When the stone is in water:
(1000 kg/m³) V (9.8 m/s²) = 2.5 N − 1.5 N
V = 1.02×10⁻⁴ m³
When the stone is in kerosene:
ρ (1.02×10⁻⁴ m³) (9.8 m/s²) = 2.5 N − 1.7 N
ρ = 800 kg/m³
The density of kerosene relative to water is 800 / 1000 = 0.8.
