5. a) (2) Draw a diagram showing the essential parts of a suction pump. 



b) (4) Explain the action of the pump, referring to the diagram. 



c) (2) What is the approximate height to which water can be raised by 



suction ? 



d) (2) What imposes a limit to the height to which water can be raised by 



suction ? 



Group II 



6. a) (2) Describe two instances in which allowance has to be made for the 



change of size of bodies with change of temperature. 



b) (2) Give an example of a practical use made of the fact that different 



solids do not all expand at the same rate. 



c) (2) What use is made of the fact that platinum and glass have practically 



the same rate of expansion ? 



d) (4) An iron steampipe is 400 cm. long. Through how many degrees 



Centigrade must it be heated to increase its length 0.4 cm. ? (Co- 

 efficient of linear expansion of iron = 0.000011 per degree C.) 



7. a) (2) Explain clearly the distinction between quantity of heat and 



temperature. 



b) (3) State a method of measuring temperature and state the facts on 



which it is based. 



c) (3) State a method of measuring quantities of heat and state the prin- 



ciple involved. 



d) (2) The normal temperature of the human body is 98|° F. Express this 



temperature on the Centigrade scale. 



8. a) (3) What transformations of energy take place in generating electricity 



from coal by a steam engine ? 



b) (2) State two ways in which energy is "lost" during these transforma- 



tions, and tell how such losses may be reduced. 



c) (5) The heat value of a certain kind of coal is 8,000 calories per gram. 



How many grams of coal must be burned under a boiler of 60 per 

 cent efficiency to heat 100,000 g. of water from 15° C. to the 

 boiling-point and to change it to steam under normal pressure ? 



Group III 



9. a) (2) What is the cause of beats in sound ? 



b) (2) How is it possible by means of beats to tune in unison two strings that 



differ slightly in pitch? 



c) (1) What is the value of the sounding board on a musical instrument ? 



d) (1) What is a fundamental tone ? 



e) (1) What is a node? 



/) (3) What is the relative loudness of the sound of the discharge of a gun 

 as heard by A a mile from the gun and as heard by B a quarter 

 of a mile from the gun ? 



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