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Questions and Answers
Newton's law of gravitation states that ______
the force of attraction between two point masses is directly proportional to the product of the masses and inversely proportional to the square of the distance between them.
Gravitational field strength at a point is defined as ___
the gravitational force per unit mass acting on that point.
Gravitational potential at a point is ____
the work done per unit mass in bringing a small test mass from infinity to that point.
Gravitational potential energy U of a body of mass m __
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As the satellite orbits the earth, it gradually loses energy because of air resistance. With reference to the total energy of the satellite, state and explain the effect of the change on the radius of the orbit: As the satellite loses total energy, it becomes more negative. Hence, the magnitude of GMm/2r (KE) ___, then r ___. Hence, the radius of orbit decreases.
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As the satellite orbits the earth, it gradually loses energy because of air resistance. Suggest why so many satellites "burn up" in the Earth's atmosphere: As r decreases, GMm/2r ___. Hence, KE increases and speed ____. There is more __, and the satellites fall faster and faster towards the ___with a smaller and smaller radius, leading to more heat generated until the satellite burns up.
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Explain why the satellite does not fall towards the earth eventho the Fg is directed toward the centre of the earth: The satellite is rotating about the earth. The force exerted by ___ on the satellite is perpendicular to the____ of the satellite, and the magnitude of this force provides the centripetal acceleration required for the satellite to orbit about the earth.
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The potential at the surface of A is smaller than that of B, (Seen on a graph A is more negative than B), hence there is loss in potential energy. By conservation of energy, the body will have a__. hence KE at A is larger than that of B.
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State and explain the distance x at which the resultant gravitational field strength due to the two stars is zero: the magnitude of the potential ____is equal to the ____ at x=...
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Explain briefly the overall shape of the graph (gravitational field strength against radius): curve is because r is___ to r^2 and they are taking left/right as positive.
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