The principles and practice of statics and dynamics1851 - 152 من الصفحات |
عبارات ومصطلحات مألوفة
accelerating force angle axis beam centre of gravity centrifugal force centripetal force circumference column cord cubic foot curve cwts density depth descend described diagonal diameter distance draw earth embankment equal equilibrium feet per second fluid force of gravity force or weight forces acting formulæ friction fulcrum F given hence horizontal inches inclined plane indefinitely small length lever magnitude and direction mercury miles per hour moment of inertia motion moveable pulley moving number of forces parabola parallel parallelogram parallelopiped particle perpendicular piston PROB PROP.-If PROP.-To find proportional radii radius represent respectively resultant screw shewn space specific gravity steam engine surface three forces tion tons train triangle units valve velocity acquired vertical vessel wall wheel and axle whence
مقاطع مشهورة
الصفحة 79 - Prove that the pressure of a uniform heavy incompressible fluid on any surface is equal to the weight of a column of the fluid, the base of which is equal to the area of the surface, and altitude equal to the depth of the centre of gravity of the surface below the surface of the fluid.
الصفحة 91 - To explain the construction of the common barometer, and to shew that the mercury is sustained in it by the pressure of the air on the surface of the mercury in the basin.
الصفحة 121 - ... Their distances, according to Kepler and Bullialdus, scarcely differ by any sensible quantity, and where they differ most the distances drawn from the periodic times fall in between them. That the circum-terrestrial force likewise decreases in the duplicate proportion of the distances, I infer thus. The mean distance of the moon from the centre of the earth, is, in semi-diameters of the earth, according to...
الصفحة 11 - But the true weight of a body may be found by a false balance in the following manner. First, weigh the body in one scale, and afterwards weigh it in the other ; then the mean proportional between these weights will be the true weight. For let x = true weight of the body, and W the number of ounces or pounds it weighs in the scale A, and w the ounces or pounds it weighs in the scale B ; then, by Art. 39, we shall have AcXx = BcXW, and BcXx = AcXtc. By multiplying these equations, there results, Ac...
الصفحة 15 - ... any weight. The pulley is either single, or combined together, to increase the power. It is also either fixed or moveable, according as it is fixed to one place, or moves up and down with the weight and power. PROPOSITION XXXIII.
الصفحة 8 - A Lever is an inflexible rod moveable only about a fixed axis ; which is called the fulcrum. The portions of the lever into which the fulcrum divides it are called the arms of the lever: when the arms are in the same straight line, it is called a straight lever; in other cases a bent lever.
الصفحة 13 - In a system of toothed wheels and axles, it in required to find the relation between the power and the weight, when they are in equilibrium. The power P is applied to the circumference of the first wheel a, which transmits its effect to the circumference of the first axle or pinion b ; this acts on the circumference of the second wheel e ; and so on through the pinion c to the wheel f, till the force is transmitted to the last axle d, which supports the weight W.
الصفحة 98 - ... while the other end is immersed in a vessel of mercury ; this tube acts as a guage, and shews by the ascent of the mercury within it, the amount of rarefaction in the receiver, because, as the rarefaction proceeds in the receiver, the elastic force of the air pressing on the mercury in the guage-tube is diminished. 234. PROP. — To find the density of the air in the receiver of an air pump after any given number of turns of the wheel. Let R be the content of the receiver and pipe, and b the...
الصفحة 11 - If the weight of the beam in the last example be 12 cwts., required the pressure on each point of support. Ans. 21 and 15f cwts.
الصفحة 3 - COH. 2. — If four forces in different planes act upon a point or body and keep it in equilibrium, these four forces are proportional to the three edges and diagonal of a parallelopiped, formed on lines respectively parallel to the directions of the forces. 25. COR. 3. — Hence a single force may be resolved into three others in different planes ; and each of these may be resolved again into others, either in the same or different planes, and so on to any extent.