Question

(a) How does a boat float in water?
(b) A piece of steel has a volume of 12 cm³, and a mass of 96 g. What is its density.
(i) in g/cm³?
(ii) in kg/m³?

Answer 1

(a) The boat floats in water because the upthrust of water on the boat is greater than the weight of the boat.

(b) (i) ρ (density of steel piece) = ?
V (volume of steel piece) = 12 cm³
m (mass of steel piece) = 96 g
$$\begin{gathered} \mathrm{\rho }=\frac{m}{V} \\ =\frac{96}{12} \end{gathered}$$
ρ = 8 g/cm³
Ans: Density of steel piece = 8 g/cm³.

(ii) We know that 1 g/cm³ = 1,000 kg/m³
So, 8 g/cm³ = 8 × 1,000 kg/m³
= 8,000 kg/m³
Ans: Density of steel piece = 8,000 kg/m³.