Physics Question

Question

The single-atom gas is contained in a cylinder whose volume can be changed by a piston. The volume of gas is

6.0 m³ and exerts a pressure of 1.0 · 10 5 Pa on the cylinder walls. Calculate the internal

energy change of the gas, if the volume of gas is 0.5 m³ and its pressure - 4.0 · 10 5 Pa!

Answer 1

Assuming it is an ideal gas (in addition to being single-atom), you can use the relation

U = (3/2)nRT ⇒ ΔU = (3/2)nR(T₂ - T₁)

T₁ = P₁V₁ / (nR)

T₂ = P₂V₂ / (nR)

ΔU = (3/2)nR [P₂V₂ / (nR) - P₁V₁ / (nR)]

ΔU = (3/2)( P₂V₂ - P₁V₁)

You have P₁, P₂, V₁, and V₂. Plug in the numbers. Use m³ for the volumes. For pressure, remember that

1 Pa = 1 newton/m².

The answer will come out in joules.