<script>on mouseUpput the short name of this card into xTempput char 2 to 6 of xTemp & ".mov" into Movie--put Movieif Movie is not empty then-- put "Videos:NASA:" & Movie into pMovieplayMovie Movie,"Videos:NASA:"end ifend mouseUp</script>
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<text><span class="style10">otion and Force (5 of 5)Gravitation</span><span class="style7">Gravitational force is one of the four fundamental forces that occur in nature. The others are electromagnetic force, and the strong and the weak nuclear forces. The electromagnetic and weak forces have recently been shown to be part of an electro-weak force.Gravitational force is the mutual force of attraction between masses. The gravitational force is much weaker than the other forces mentioned above. However, this long-range force should not be thought of as a weak force. An object resting on a table is acted on by the gravitational force of the whole Earth - a significant force. The almost equal force exerted by the table is the result of short-range forces exerted by molecules on its surface.</span><span class="style26">Newton's law of gravitation</span><span class="style7"> was first described in his </span><span class="style26">Philosophiae Naturalis Principia Mathematica</span><span class="style7"> (`The Mathematical Principles of Natural Philosophy'), which he wrote in 1687. Newton used the notion of a </span><span class="style26">particle</span><span class="style7">, by which he meant a body so small that its dimensions are negligible compared to other distances. He stated that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. The constant of proportionality is represented by </span><span class="style26">G</span><span class="style7"> and is known as the </span><span class="style26">gravitational constant</span><span class="style7">. The law is an `inverse-square law', since the magnitude of the force is inversely proportional to the square of the distance between the masses. A similar inverse-square law applies for the force between two electric charges.Newtonian mechanics were so successful that a mechanistic belief developed in which it was thought that with the know ledge of Newton's laws (and later those of electromagnetism) it would be possible to predict the future of the Universe if the positions, velocities and accelerations of all particles at any one instant were known. Later the quantum theory and the Heisenberg Uncertainty Principle confounded this belief by predicting the fundamental impossibility of making simultaneous measurements of the position and velocity of a particle with infinite accuracy. ASTHE KINEMATICEQUATIONSFor a body moving in a straight line with uniformly accelerated motion: 1. v = u + at 2. s = ut + 1/2 at<2> 3. v <2> = u <2> + 2as 4. s = 1/2 t (u + v) where s = displacement t = time u = initial or starting velocity v = velocity after time t a = accelerationNEWTON'S LAWS OFMOTION1.A body will remain at rest or traveling in a straight line at constant speed unless it is acted upon by an external force.2.The resultant force exerted on a body is directly proportional to the acceleration produced by the force.F = ma where F is the force exerted, m is the mass of the body a is the acceleration v1 is the initial velocity v2 is the final velocity 3.To every action there is an equal and opposite reaction.NEWTON'S LAW OFGRAVITATIONEvery particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. F = G m1 m2 ----------- x to the power of 2where F is the force m1, m2 are the masses x is the distance between the particles.</span></text>
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<text><span class="style10"> pen and magnet are dropped in low gravity. </span><span class="style7">They float in mid air and are attracted to each other due to magnetic forces.</span></text>
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<text>ΓÇó THE HISTORY OF ASTRONOMYΓÇó FORCES AFFECTING SOLIDS AND FLUIDSΓÇó THERMODYNAMICSΓÇó QUANTUM THEORY AND RELATIVITYΓÇó THE HISTORY OF SCIENCEΓÇó FUNCTIONS, GRAPHS AND CHANGE</text>
