Question

A cubical block of wood of side 10 cm floats at the interface between oil and water with its lower surface 1.5 cm below the interface. The density of the oils is 790 kg m^-3. What is the density of the block ?

• A. 812.5 kg m^-3
• B. 800.5 kg m^-3
• C. 820 kg m^-3
• D. None

Answer 1

Answer: (A)

812.5 kg m^-3

Answer 2

M = 1.5 × 100 + 8.5 × 100 × .79 = 821.5 g

ρ = $\frac { 821.5 \times 10 ^ { - 3 } } { 10 ^ { 3 } \times 10 ^ { - 6 } }$ = 821.5 kg m^-3