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1920 

 PHYSICS 



Friday, June 25 2 p.m. Two hours 



Answer ten questions as indicated below. No extra credit will be given for more than 

 ten questions. 



Indicate clearly your reasoning in each problem and state the units in which each 

 answer is expressed. 



Number and letter each answer to correspond with the question selected. 



Group I 

 (Omit one question from this group.) 



1. a) Distinguish between mass and weight. 



h) Could the fact that the weight of a body changes if it is taken from the 

 equatorial to the polar region of the earth be shown by either a spring 

 balance or a beam balance ? Explain. 



2. A body having a volume of 100 cubic centimeters and a density of 2.5 is 



fastened to a block of wood having a volume of 200 cubic centimeters 

 and a density of 0.5. 



a) What will the combination weigh when immersed in water ? 



b) What will the combination weigh when immersed in oil of density 0.9 ? 



3. a) Represent by a diagram a system of pulleys consisting of a double fixed 



block and a single movable block. 

 b) If the efiiciency of the above system is 70 per cent, how great a weight 



can be lifted by a force of 30 pounds apphed to the free end of the 

 rope? 



4. What horse power is required to run an automobile on a level road at the rate 



of 30 miles per hour if the forces of friction amount to 125 pounds ? 



Group II 



{Omit one question from this group.) 



5. a) How are sounds produced and how are they transmitted to the ear ? 



b) How does the intensity of sound vary with change of distance from the 

 source ? 



6. a) If the lowest tone which the ear can recognize has a frequency of 16 



vibrations per second what is the length of the longest wave the ear 

 perceives in air at a temperature of 0° C. ? 



b) What effect, if any, does change in temperature produce in the velocity 

 of sound in air ? 



(THIS EXAMINATION IS CONTINUED ON PAGE 2) 

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