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GCE A-Level物理课程大纲

Chapter 7: Gravitational Field


The Gravitational Field
Gravitational force between point masses
Gravitational field of a point mass
Gravitational field near the surface of the earth
Gravitational potential
Circular orbits



(a) Show an understanding of the concept of a gravitational field as an example of field of force and define the gravitational field strength at a point as the gravitational force exerted per unit mass placed at that point.

(b) Recognize the analogy between certain qualitative and quantitative aspects of gravitational and electric fields.

(c) Recall and use Newton’s law of gravitation in the form F = Gm₁m₂/r²

(d) Derive, from Newton's law of gravitation and the definition of gravitational field strength, the equation g = GM/r² for the gravitational field strength of a point mass.

(e) Recall and apply the equation g = GM/r² for the gravitational field strength of a point mass to new situations or to solve related problems.

(f) Show an understanding that near the surface of the Earth, gravitational field strength is approximately constant and is equal to the acceleration of free fall.

(g) Define the gravitational potential at a point as the work done per unit mass in bringing a small test mass from infinity to that point.

(h) Solve problems using the equation φ = - GM/r for the gravitational potential in the field of a point mass.

(i) Analyze circular orbits in inverse square law fields by relating the gravitational force to the centripetal acceleration it causes.

(j) Show an understanding of geostationary orbits and their application.

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