Page 76 - SP015 Past Years PSPM Chapter 6 -14 Ver 2020

PHYSICS PSPM SEM 1 1999 - 2017

PSPM 2012/2013 SF016/2 No. 8(d)(ii), (iii)

25. (a) In an isovolumetric process, a system is supplied with 250 J of heat. What is the
change in its internal energy? [2 m]

3
-4
(b) What is the work done by 1.56  10 moles of ideal gas that expands from 65 cm
3
to 135 cm at a constant temperature of 40 C? [3 m]

PSPM 2013/2014 SF016/2 No. 8(d)

26. p (N m )
-2

8  10 B C
4

4
2  10 A

-3 -3 3
2  10 6  10 V (m )

FIGURE 14.5

FIGURE 14.5 shows a p-V graph for a series of thermodynamic processes, ABC. In
process AB and BC, 160 J and 600 J are added to the system respectively. Calculate the
change of the internal energy during the process ABC. [5 m]

PSPM 2014/2015 SF016/2 No. 8(d)

5
27. A 15 liter gas cylinder contains helium gas with pressure 1.01  10 Pa at 25 C. When
heated, the gas undergoes an isochoric process.

(a) Calculate the mass of helium gas. The atomic molar mass of helium gas is 4 g.
[2 m]

(b) If 500 J of heat is added, calculate the change in the internal energy of the gas and
sketch the graph of pressure versus volume for the isochoric process. [2 m]

5
(c) If the gas cylinder can withstand a pressure up to 4.55  10 Pa, calculate the
maximum quantity of gas at 45 C. [2 m]

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