Question

One kg of adiatomic gas is at a pressure of 5 × 105 (N / m2) The density of the gas is {(5kg) / m3} what is the energy of the gas due to its thermal motion ?

(A) 2.5 × 105 J

(B) 3.5 × 105 J

(C) 4.5 × 105 J

(D) 1.5 × 105 J

Answer 1

Correct option: (A) 2.5 × 105 J

Explanation:

P = 5 × 105 N/m2

ρ = 5 kg/m3 hence volume = v = (m/ρ) = [(1 kg) / (5 kg/m3)] = (1/5) m3

For diatomic gas, CV = (5/2).

Thermal energy = CV ∙ nRT

= (5/2) nRT

As PV = nRT

∴ Thermal energy = (5/2)PV = (5/2) × 5 × 105 × (1/5)

= 2.5 × 105 J