5. a) (8) A tank having a volume of 12 cu. ft. contains air under a pressure of 



30 lbs. per sq. in. On connecting the tank to an exhausted recepticle 

 the air pressure is reduced to 10 lbs. per sq. in. Find the volume of 

 the recepticle. 

 h) (2) Describe two phenom.ena that are caused by surface tension. 



Group II 



6. a) (2) Define coefficient of linear expansion. 



b) (8) Describe an experimental method of measuring the coefficient of 



linear expansion of a solid, describing the apparatus used, the 

 measurements made, and the way in which these measurements are 

 used to compute the coefficient. 



7. a) (6) A balloon is filled on a cool night with 20,000 cu. ft. of gas at a tempera- 



ture of 7° C. under a pressure of 15 lbs. per sq. in. In the sunshine 

 of the day the gas becomes warmed. At what temperature will 

 the pressure reach 16 lbs. per sq. in. ? Assume that the gas bag 

 does not stretch and that no gas escapes. 

 h) (2) Express 9° C. on the Fahrenheit scale. 



c) (2) Compare the advantages of mercury and of air as thermometric 



substances. 



8. (j) (2) Name and define a unit quantity of heat. 



b) (8) A copper calorimeter of mass 210 g. contains 85 g. of water and 100 g. 

 of lead shot at 15° C. How much boiling water must be added to 

 raise the temperature of the calorimeter and contents to 25° C. ? 

 (Sp. ht. of copper =0.095; of lead = 0.032.) 



Group III 



9. a) (2) What conditions are necessary for the formation of an echo ? 



b) (2) What is the physical difference between a noise and a musical sound ? 



c) (2) Why is thunder usually heard some time after a lightning flash is seen ? 



d) (2) Upon what does the loudness of sound depend? 



e) (2) Upon what does the pitch of a sound depend ? 



Group IV 

 10. a) (3) A more sharply defined shadow is cast by an opaque body when the 



source of Hght is an arc lamp than when it is a gas jet. Explain 



by the aid of diagrams. 

 h) (3) What should be the brightness of a single light in the ceiling 10 ft. 



from a book to give the same illumination as two candles placed 



one foot from the book ? 

 c) (4) Ex-plain what is meant by saying that the index of refraction of 



water is |. Make a careful, fully labeled diagram showing the 



passage of a ray of light obliquely from air into water. 



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IZC) 



