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7. A piece of glass (specific heat =0. 19) weighing 3 kg. and at a temperature of 



— 30° C. is placed in water at 0° C. Neglecting the heat effects upon the 

 containing vessel find how much water will be converted into ice at 0° C. 



8. Two kilograms of shot having specific heat of 0.031 are dropped 70 meters. 



The temperature of the shot is found to have risen 5.3° C. On the 

 supposition that all the heat generated was retained by the shot, calculate 

 the mechanical equivalent of heat. 



Group III 



9. On a day when the thermometer stood at 15° C. a projectile moving forward 



with an average velocity of 1700 ft. per sec. was heard by the gunner to 

 strike its target 5 sec. after it left the gun. What was the distance from 

 the gun to the target ? 



Group IV 



10. Describe with the aid of a diagram a method for determining the position and 



size of the image of an object produced by a plane mirror. 



11. c) What kind of a mirror will produce an erect image of an object one-half of 



its natural size when the object is 10 in. from the mirror ? 



b) WTiat is the radius of curvature of the mirror ? 



12. A candle is 8 in. from a lens. Its real image is 40 in. from the lens. Show 



from calculation and diagram the relative positions of lens image, and 

 object and the relative sizes of the image and the object. 



Group V 



13. A single closed loop of wire lies in a horizontal plane, and through it is dropped 



a bar magnet whose north pole is pointing downward. 



a) Show by a diagram the direction of the current induced in the wire while 



the magnet is approaching the loop ? State the law illustrated by this 

 experiment. 



b) What factors determine the magnitude of this current ? 



14. A circuit consists of the following four parts joined in series: an ammeter of 



negligible resistance; a cell with an internal resistance of 0.8 ohms; a pair 

 of wires, of 4 ohms and 6 ohms resistance respectively, joined in parallel; 

 a 1-ohm coil. The connecting wires have a resistance of 0.2 ohm. Make 

 a labeled diagram of the circuit. 



a) If the electromotive force of the cell is 1 . 4 volts, what is the reading of the 



ammeter ? 



b) How much current flows through each of the two wires which are joined in 



parallel ? 



15. An incandescent lamp has a resistance of 275 ohms when connected with a 



110-volt circuit. 



a) If the lamp takes 1 . 25 watts per candle power, what is its candle power ? 



b) How much heat is developed in the lamp per minute ? 



I3« 



