Page 75 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PSPM SP015

PSPM 2008/2009 SF017/2 No. 8

20. A gas filled metal container shrinks when it is cooled.
(a) What happen to the internal energy of the gas? [1 m]

(b) Is it the surrounding or the gas that does the work? Explain your answer. [2 m]

PSPM 2008/2009 SF017/2 No. 14(d)(ii), (iii)

21. One mole of N 2 gas at 0 C is heated to 90 C at constant pressure. The change in
internal energy is 1863 J. Calculate
(a) the work done by the gas. [2 m]

(b) the heat added to the gas. [2 m]

PSPM 2009/2010 SF017/2 No. 8

22. A gas expands isothermally from volume V 1 to volume V 2 and performs mechanical
work 1200 J.

(a) Sketch the p-V graph of this process. [2 m]

(b) Calculate the heat gained by the gas. [2 m]

PSPM 2010/2011 SF017/2 No. 14(b)

23. One cubic meter air initially at 27 C and atmospheric pressure is compressed
isothermally to half of its original volume. Then the air is allowed to expand
isobarically back to its original volume.

(a) Using the same axes, sketch and label a p-V diagram of these two thermodynamic
processes. [3 m]
(b) Calculate the pressure of the air after the isothermal compression. [2 m]

(c) Calculate the final temperature of the air. [2 m]

(d) Calculate the total work done for the whole process. [7 m]

PSPM 2011/2012 SF016/2 No. 8(c)(iii)

3
3
24. Three moles of an ideal gas expands from 50 cm to 120 cm at a constant temperature
of 30 C. Calculate the heat transferred to the surroundings by this process. [3 m]

75