The Principles of Mechanics: Explaining and Demonstrating the General Laws of Motion, the Laws of Gravity, Motion of Descending Bodies, Projectiles, Mechanic Powers, ...

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J. Richardson, 1758 - 284 pàgines
 

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I
6
II
21
III
30
V
45
VII
59
IX
73
XI
85
XII
91
XIV
108
XVI
134
XVIII
151
XIX
160
XXI
173

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Pàgina 53 - For since the time of vibration is to the time of descent through half the length of the pendulum, as the circumference of a circle to its diameter, that is, as 3.14159 to 1?
Pàgina iii - I wish we could derive the rest of the phenomena of Nature by the same kind of reasoning from mechanical principles, for I am induced by many reasons to suspect that they may all depend upon certain forces by which the particles of bodies, by some causes hitherto unknown, are either mutually impelled towards one another, and cohere in regular figures, or are repelled and recede from one another.
Pàgina 167 - For on this principle depends the mechanism or contrivance of mechanical engines, used to draw or raise heavy bodies, or overcome any other force. The whole design of these being to give such a velocity to the power in respect of the weight, as that the momentum of the power may exceed the momentum of the weight. For, if machines are so contrived that the velocities of the agent and...
Pàgina 167 - ... so adjusted, that when the weight and power are put in motion on the machine, the velocity of the power may be at least so much greater than that of the weight, as the weight and friction of the machine, taken together, is greater than the power. For on this principle depends the mechanism or contrivance of mechanical engines, used to draw or raise heavy bodies, or overcome any other force. The whole design of these being to give such a velocity to the power in respect of the weight, as that...
Pàgina 168 - ... provided the elbow of one of the handles be at right angles to that of the other. And with a fly, or heavy wheel, applied to it, a man may do...
Pàgina 15 - ... which struck the water, that is to say the angle of reflection will be equal to the angle of incidence.
Pàgina ii - And he made in Jerusalem engines, invented by cunning men, to be on the towers and upon the bulwarks, to shoot arrows and great stones withal.
Pàgina 165 - V™ or as */n. 6. As to the mechanic powers : the single lever makes no resistance by friction ; but if, by the motion of the lever in lifting, the fulcrum or place of support be changed further from the weight, the power will be decreased thereby. 7. In any wheel of a machine, running upon an axis, the friction on the axis is as the weight upon it, the diameter of the axis, and the angular velocity. This sort of friction is but small. 8. In the pulley, if p...
Pàgina 168 - ... of continuous bodies that are to be separated, or from the weights of bodies to be raised, the excess of the force remaining, after all those resistances are overcome, will produce an acceleration of motion proportional thereto, as well in the parts of the machine as in the resisting body.
Pàgina 166 - P+9 pulley, and it is not increased by the acceleration of the weight 9, but remains always the same. The friction of the pulley is very considerable, when the sheaves rub against the blocks, and by the wearing of the holes and axles. The friction on the axis of the pulley is as the weight W, its angular velocity, the diameter of the axis directly, and the diameter of the pulley inversely. A power of lOOlb.

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