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1919 

 PHYSICS 



Monday, September 15 2-5 p.m. 



Answer ten numbered questions, distributed as follows: three from Group I, two from 

 Group II, two from Group IV, two from Group V, and any one of the remaining questions. 



Show clearly the method by which you obtained your answers to problems and state 

 the units used in each case. 



Attach to the answer, in each case, the number and letter used in the printed paper. 



Group I 



1. A stone of specific gravity 2.5, weighing 300 lbs. in air, rests on the bottom 



of a pond. What work will be done in raising the stone 10 ft. through the 

 water ? 



2. A tapering telephone pole 24 ft. long is supported at each end in a horizontal 



position. The pressure on one support is 200 lbs., and on the other sup- 

 port 120 lbs. 



a) Locate the center of gravity of the pole. 



b) If it were supported at its center of length only, what would be the least 



force that might be applied to the pole that would keep the pole hori- 

 zontal ? 



3. An automobile accelerates from rest to 45 miles an hour in 15 seconds. 



a) If this acceleration is uniform find its value in feet per second per second. 



b) What distance did the car go in the first 15 seconds ? 



4. What horse-power must be used to pull a body weighing 5 tons along a hori- 



zontal surface at the rate of 6 miles per hour, the coefficient of friction 

 being 0.2? 



5. Water is pumped into the bottom of an air-tight tank having a capacity of 



1000 gals., compressing the air above it from a pressure of 15 lbs. per 

 square inch to a pressure of 50 lbs. per square inch. 



a) How much water is pumped into the tank ? 



b) If 200 gals, of water are now drawn off, what will be the air pressure in the 



tank? 



Group II 



6. a) Explain under what conditions frost will form on the inside surface of a 



window of a house and not on the outside surface. 



b) Explain the cooling of a liquid by evaporation. 



c) The volume of a mass of gas is 200 cu. cm. at 27° C. At what tempera- 



ture will its volume be 250 cu. cm., if the pressure is maintained con- 

 stant? 



(THIS EXAMINATION IS CONTINUED ON PAGE 2) 



