A laboratory manual in physics, to accompany Black and Davis' "Practical physics for secondary schools," (1913)
Black, Newton Henry, 1874- [from old catalog] · New York, The Macmillan company · leaf 95
e pulley times therevolutions per minute. The workdone in one minute is equal to thefriction times the distance per minute.First determine the circumferenceof the pulley by measuring the length of fine wire requiredto make one turn around the pulley. To determine thenumber of revolutions per… … Fig. 49 EFFICIENCY OF AN ELECTRIC MOTOR 81 tension on the brake cord so as to slow down themotor a little. Keeping this pull steady, we getthe speed of the motor and at the same time readthe spring balances, ammeter and voltmeter. Thenrepeat this experiment, putting more load on themotor by pulling…
Physics
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