DP Physics (last assessment 2024)
Question 18N.3.SL.TZ0.b
| Date | November 2018 | Marks available | [Maximum mark: 3] | Reference code | 18N.3.SL.TZ0.b |
| Level | SL | Paper | 3 | Time zone | TZ0 |
| Command term | Show that | Question number | b | Adapted from | N/A |
b.
[Maximum mark: 3]
18N.3.SL.TZ0.b
The pV diagram of a heat engine using an ideal gas consists of an isothermal expansion A → B, an isobaric compression B → C and an adiabatic compression C → A.
The following data are available:
Temperature at A = 385 K
Pressure at A = 2.80 × 106 Pa
Volume at A = 1.00 × 10–4 m3
Volume at B = 2.80 × 10–4 m3
Volume at C = 1.85 × 10–4 m3
Show that the thermal energy transferred from the gas during the change B → C is 238 J.
[3]
Markscheme
work done = «pΔV = 1.00 × 106 × (1.85 × 10−4 − 2.80 × 10−4 =» −95 «J» ✔
change in internal energy = «pΔV = − × 95 =» −142.5 «J» ✔
Q = −95 − 142.5 ✔
«−238 J»
Allow positive values.
