DP Physics (last assessment 2024)

Question 19N.3.SL.TZ0.6b(i)

Date	November 2019	Marks available	[Maximum mark: 3]	Reference code	19N.3.SL.TZ0.6b(i)
Level	SL	Paper	3	Time zone	TZ0
Command term	Determine	Question number	b(i)	Adapted from	N/A

b(i).

[Maximum mark: 3]

19N.3.SL.TZ0.6b(i)

An ideal gas consisting of 0.300 mol undergoes a process ABCD. AB is an adiabatic expansion from the initial volume V_A to the volume 1.5 V_A. BC is an isothermal compression. The pressures at C and D are the same as at A.

The following data are available.

Pressure at A = 250 kPa
Volume at C = 3.50 × 10^–3 m³
Volume at D = 2.00 × 10^–3 m³

The gas at C is further compressed to D at a constant pressure. During this compression the temperature decreases by 150 K.

For the compression CD,

(b(i))

determine the thermal energy removed from the system.

[3]

Markscheme

ALTERNATIVE 1

work done $∆ W = « - » 250 \times 10^{3} \times 1.5 \times 10^{- 3} = « - » 375 « J »$ ✔

change in internal energy $∆ U = \frac{3}{2} \times 0.300 \times 8.31 \times (- 150) = « - » 561 « J »$
OR
$∆ U = \frac{3}{2} P ∆ V = \frac{3}{2} \times 375 = « - » 563 « J »$ ✔

thermal energy removed $∆ Q = 375 + 561 = 936 « J »$
OR
$∆ Q = 375 + 563 = 938 « J »$ ✔

ALTERNATIVE 2

$∆ Q = « n C p ∆ T = » \frac{5}{2} \times n R T$ ✔

thermal energy removed $∆ Q = 0.300 \times 2.5 \times 8.31 \times 150$ ✔

$= 935 « J »$ ✔

Syllabus sections

Option B: Engineering physics

Option B: Engineering physics » Option B: Engineering physics (Core topics) » B.2 – Thermodynamics

Option B: Engineering physics » Option B: Engineering physics (Core topics)

Question 19N.3.SL.TZ0.6b(i)

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