Question

On heating a glass block of 10⁵ cm³ from 25°C to 40°C its volume increases by 4 cm³. Calculate the coefficient of 

(i) Cubical expansion and 

(ii) Linear expansion

Answer 1

Volume V₀ = 10⁵ cm³ 

Change in temperature ΔT = 40 – 25 = 15°C 

Change in volume ΔV = 4 cm³ 

(i) The coefficient of cubical expansion is

\(a_V = \frac{Δ V}{V_0 Δ T}\)

\(a_V = \frac{4}{{10^5\times 15}}\) = 26.67 x 10^-6 /°C

α_V = 26.67 × 10^-6 /°C

(ii) Coefficient of linear expansion is

a_L = \(\frac{aV}{3}\)

\(a_L = \frac{26.67}{3}\times 10^{-6}\)

\(a_L\) = 8.89 x 10^-6 /°C