PHYSICS 



Tuesday 4.15-6. 15 p. m. 



A teacher's certificate covering the laboratory instruction must be presented as part 

 of the examination. 



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

 than ten questions. 



GROUP A. (Omit one question from this group.) 



1. State the law of the conservation of energy. 



Explain how change of energy of one sort into energy of another sort is 

 illustrated when a ball is thrown vertically upward. 



2. A lump of metal weighs 160 grams in air, 140 grams in water, and 146 grams 



in oil. Find the specific gravity of the metal and that of the oil and also 

 the volume of the metal. 



3. A body weighing 120 pounds rests on an inclined plane the length of which 



is 10 feet, the height 6 feet, and the base 8 feet. 

 Neglecting friction find: 



a) The pressure which the body exerts perpendicular to the plane; 



b) The force exerted parallel to the plane; 



c) How much work must be done to move the body from the bottom to the 



top of the plane. 



4. A windlass has a drum 6 inches in diameter and a crank arm 1 2 inches long. 

 Neglecting friction find: 



a) What force applied to the crank arm is required to support a loo-pound 



weight; 



b) What would be the efficiency of the windlass if a force of 30 pounds was 



found necessary to raise the weight. 



GROUP B. (Omit one question from this group.) 



5. How does sound differ from light in respect to 



a) The nature of the medium required ? 



b) The character of the motion of the medium ? 



c) Velocity? (The approximate velocity of each should be given.) 



6. A blow struck upon a steel cable was heard through the cable in o. 2 seconds 



and through the air in 3 seconds. The temperature was o C. 



a) How far from the observer was the blow struck ? 



b) What was the speed of sound in the cable ? 



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