Elementary Physics

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Sheldon, 1878 - 317 páginas
 

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Página 377 - ... laws: (1.) The angle of incidence is equal to the angle of reflection. (2.) The incident and reflected rays are both in the same plane, which is perpendicular to the reflecting surface.
Página 31 - Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.
Página 72 - A cycloid is the curve traced by a point in the circumference of a circle rolling along a straight line. The pendulum may be made to move in such an arc by suspending a small heavy ball by FIG.
Página 377 - To look at anything means to place the eye in such a position that the image of the object falls on the small region of perfectly clear vision. This we may call direct vision, applying the term indirect to that exercised with the lateral parts of the retina — indeed with all except the yellow spot.
Página 235 - Oxygen and hydrogen combine in the proportion of one volume of the former, to two of the latter, to form water.
Página 435 - ... to the mountain-top, where the heat absorbed in vaporization is given out in condensation, while that expended by the sun in lifting the water to its present elevation is still unrestored. This we find paid back to the last unit by the friction along the river's bed ; at the bottom of the cascades where the plunge of the torrent is suddenly arrested ; in the warmth of the machinery turned by the river ; in the spark from the millstone ; beneath the...
Página 162 - The BAROSCOPE consists of a beam like that of a balance, from one extremity of which is suspended a hollow sphere of copper, and from the other extremity a solid sphere of lead. These are made to balance each other in the atmosphere. If the instrument be placed under the receiver of an air-pump and the air exhausted, the copper sphere will descend.
Página 391 - Note. — In constructions for curved mirrors, we have chosen two particular rays for each focus sought ; one perpendicular to the mirror, the other parallel to the principal axis. This was only for the sake of convenience. Any two or more incident rays might have been taken and the direction of the reflected rays determined by making the angle of reflection equal to the angle of incidence. EXERCISES. 1. What must be the angle of incidence that the angle between the incident and the reflected rays...
Página 44 - ... weight in the same direction. Determine its value. 2. In similar manner, represent the resultant of the same forces when the men pull in opposite directions. Determine its value. 3. Suppose an attempt is made to row a boat at the rate of 4 miles an hour directly across a stream flowing at the rate of 3 miles an hour. Determine the direction and velocity of the boat. 4. A flag is drawn steadily downward 64 feet from the masthead of a moving ship.

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