JAMB - Physics (1992 - No. 9)
If a plastic sphere floats in water (density = 1000kgm3) with 0.5 of its volume submerged, and floats in oil with 0.4 of its volume submerged the density of the oil is
800kgm3
1200kgm3
1250kgm3
2000kgm3
Wyjaśnienie
since the plastic sphere floats on both liquids, it displaces the amount of liquid equal to its mass in each case
∴ Mass of oil displaced = mass of water displaced
ρ x 0.4v = 1000 x 0.5v
ρ = \(\frac{ 1000 \times 0.5v}{0.4v}\)
ρ = 1250k\(gm^{-3}\)