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Thermal Physics Ii Question Paper

Thermal Physics Ii

Course:Bachelor Of Education Science

Institution: Kenyatta University question papers

Exam Year:2009

KENYATTA UNIVERSITY
UNIVERSITY EXAMINATIONS 2008/2009
INSTITUTE OF OPEN LEARNING
EXAMINATION FOR THE DEGREE OF BACHELOR OF SCIENCE AND
BACHELOR OF EDUCATION
SPH 307: THERMAL PHYSICS II
DATE: TUESDAY 11TH AUGUST 2009 TIME: 8.00 A.M. – 10.00 A.M.
INSTRUCTIONS:
Answer question one which is compulsory and any other two questions.
All questions carry 20 marks each.
Q.1 a) State the first and second laws of thermodynamics. (4 marks)
b) Cite three important kinds of expansion and compression that can occur in a
gas. (6 marks)
c) Show that the work done by a gas expanding at the constant pressure P from
VI to V2 is expressed by W=P (v2 – v1) (10 marks)
Q.2 a) Explain what you understand about a carnot engine. (5 marks)
b) The carnot engine utilizes only isothermal and adiabatic processes in its
operating cycle. Explain.
c) A carnot engine absorbs 1.5 MJ of heat from a reservoir at 300oc and exhausts
heat to a reservoir at 150oc. Find out the work it performs. (10 marks)
Q.3 a) Describe the operating cycle of a gasoline engine with the help of a P – V
diagram. (6 marks)
b) What is the working fluid? Give at least three examples. (5 marks)
c) Steam at a pressure of 1.5 x 107 Nm-2 has an enthalpy of 3309 kJ/kg, find
the temperature, the specific volume and the internal energy. (9 marks)
Page 2 of 2
Q.4 a) Define and explain the concept of the heat engine. (5 marks)
b) What is entropy? (5 marks)
c) In a steam turbine, the initial pressure and temperature of a steam are 2 x 106
Nm-2 and 4000c respectively. It is expanded adiabatically to a pressure of
4 x 105 Nm2 and temperatures of 2500C. Compute
i) Isotropic efficiency of the process
ii) Loss of availability temp. of 15oC
iii) Effectiveness of the process (neglect change in K.E and P.E).
(10 marks)
Q.5 a) Explain the operation of a refrigerator. (6 marks)
b) In an effort to cool a kitchen during hot weather the refrigerator door is left
open and the kitchen’s door and window are closed. Explain what is expected
to occur. (6 marks)
c) A 1 KW refrigerator whose efficient of performance is 2.0 tales heat from a
freezer compartment at – 20o C and exhausts it at 40o C. How does its CP
compare with that of an ideal refrigerator. (8 marks)

Thermal Physics Ii Question Paper

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