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2 marksFirst Law of Thermodynamics

CAPE Physics Unit 1 · May/June 2024 · Paper 2 · Question 3(d)(i)

One mole of an ideal monoatomic gas (Cv = 3/2 R) undergoes a rectangular thermodynamic cycle from State 1 to 4 as shown in Figure 6. T₁ = 273 K, T₃ = 1092 K, p = 1.01 × 10⁵ N m⁻², and V = 0.0225 m³.

Calculate the work done during the cycle.

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Other parts of this question

  1. 3(a)Write the equation of state for an ideal gas, stating the meaning of EACH symbol.[3 marks]
  2. 3(b)(i)Complete Column 3 of Table 2 by calculating the volume of gas, V/mm³.[1 mark]
  3. 3(b)(ii)On the grid provided in Figure 5, plot a graph of volume of gas, V, versus temperature, t, using scales ranging from -325 °C to +100 °C on the temperature axis…[4 marks]
  4. 3(b)(iii)From the graph in 3(b)(ii), determine the temperature at which the volume is 0 mm³.[2 marks]
  5. 3(b)(iv)State whether it is possible to achieve a state of zero volume for the gas if it is cooled sufficiently. Justify your response.[2 marks]
  6. 3(b)(v)State the gas law which explains the observations in this experiment.[2 marks]
  7. 3(c)The first law of thermodynamics is given by ΔU = Q + W. Explain the meaning of EACH symbol when applied to the heating of a fixed mass of gas.[3 marks]
  8. 3(d)(ii)Calculate the temperature, T₂, at State 2.[3 marks]
  9. 3(d)(iii)Calculate the energy added as heat during the process from State 1 to State 2.[4 marks]
  10. 3(d)(iv)Derive an expression for Cₚ for the gas in terms of R.[2 marks]
  11. 3(d)(v)State TWO reasons why the cycle in Figure 6 is NOT 100% efficient.[2 marks]

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