A First Course in Physics

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Page 1 - I often say that when you can measure what you are speaking about and express it in numbers you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind...
Page 94 - Newton's first law of motion: <•• « > " Every body continues in its state of rest or uniform motion in a straight line, except in so far as it is compelled to change that state by force impressed upon it.
Page 328 - It will be seen from the above that the number of beats per second is equal to the difference in the vibration numbers of the two forks.
Page 356 - And show me how they calculated the initiatory speed of our car?" "Yes, my worthy friend; taking into consideration all the elements of the problem, the distance from the center of the earth to the center of the moon...
Page 83 - Any two bodies in the universe attract each other with a force which is directly proportional to the product of the masses and inversely proportional to the square of the distance between them.
Page 22 - Archimedes stated that a body immersed in a fluid is buoyed up by a force equal to the weight of the displaced fluid.
Page 79 - For in § 79 it was shown that if any one force is to have the same effect upon a body as two forces acting simultaneously, it must be represented by the diagonal of a parallelogram the sides of which represent the two forces. Hence, conversely, if two forces are to be equivalent in their...
Page 3 - The meter was intended to be one ten-millionth of the distance from the equator to the north pole, but more careful measurements show that this distance is 10,001,887 meters.
Page 9 - Distinction between density and specific gravity. The term "specific gravity" is used to denote the ratio between the weight of a body and the weight of an equal volume of water.* Thus, if a...
Page 132 - The erg is the amount of work done by a force of 1 dyne when it moves the point on which it acts 1 centimeter. To raise 1 liter of water from the floor to a table 1 meter high would require 1000 x 980 x 100 = 98,000,000 ergs of work. It will be seen, therefore, that the erg is an exceedingly small unit. For this reason it is customary to employ a unit which is equal to 10,000,000 ergs. It is called a joule, in honor of the great English physicist James Prescott Joule (1818-1889). The work done in...

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