ما يقوله الناس - كتابة مراجعة
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action of gravity areas described axes axis ball body called centre of gravity centre of moments centre of parallel centrifugal force circular sector co-ordinates collision components compound pendulum conceive conditions of equilibrium consider cord cos2 curve describe the line determine diagonal distance drawn employed equa equal and parallel equal to zero equation evidently expressed fixed point forces act forces applied given forces gonal impulse inclined plane inertia infinitely small instant intensity of gravity intersection lever machine material point middle point moving number of forces opposite sense oscillations osculating circle parallel forces parallelogram particles perpendicular plane of xy points of application polygon position proportion pulleys quantities of motion radius vector represented respectively resultant right angles screw sector similar triangles simple pendulum situated space described straight line suppose surface tend to turn three forces tion turn the system velo velocity lost vertical weight
الصفحة 80 - ... two planets are to each other as the cubes of their mean distances from the sun.
الصفحة 27 - ... the areas described by the radius vector are proportional to the times employed in describing them.
الصفحة 41 - ... directions of the forces sensibly parallel : whence we must conclude, that the line of direction of the resultant of two parallel forces is in the plane of the forces, is parallel to the direction of the forces, and that the moment of the resultant, taken in reference to any point in the plane of the forces, is equal to the sum or difference of the moments of the components, according as they tend to turn the system in the same or opposite directions about the centre of moments.
الصفحة 33 - MR = / cos2 n ; that is, the diminution of gravity, due to the centrifugal force at any place on the earth's surface, is equal to the centrifugal force at the equator, multiplied by the square of the cosine of the latitude of the place.
الصفحة 52 - Hence the moment of inertia of a body with respect to any axis, is equal to its moment of inertia with respect to...
الصفحة 31 - The point of application of the resultant of a system of parallel forces is called the centroid or center of the system of forces.
الصفحة 80 - In this case, it is obvious that the plane of the circle of illumination would be perpendicular to a line drawn from the centre of the sun to the centre of the earth...
الصفحة 10 - To find the resultant of two parallel forces. The resultant is in the same plane with, and parallel to, the components. It is their sum or difference according as they act in the same or contrary directions; and in the latter case its direction is that of the greater component. To find its line of action by construction, proceed as follows : — Fig.
الصفحة 86 - Poincare speaks of the porosity of matter as follows : "The astronomical universe consists of masses, undoubtedly of great magnitude, but separated by such immense distances that they appear to us as material points ; these points attract each other in the inverse ratio of the squares of their distances, and this attraction is the only force which affects their motion. But if our senses were keen enough to show us all the details of the bodies which the physicist studies, the spectacle thus disclosed...