ASRJC Gravitational Field Notes

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 7-1 Additional Notes Topic 7 Gravitational Field Content • Gravitational Field • Gravitational force between point masses • Gravitational field of a point mass • Gravitational field near to the surface of the Earth • Gravitational potential • Circular orbits Learning Outcomes: Candidates should be able to: (a) show an understanding of the concept of a gravitational field as an example of field of force and define gravitational field strength at a point as the gravitational force exerted per unit mass placed at that point. (b) recognise the analogy between certain qualitative and quantitative aspects of gravitational and electric fields. (will be discussed in JC2) (c) recall and use Newton's law of gravitation in the form = 12 2 Gm mF r . (d) derive, from Newton's law of gravitation and the definition of gravitational field strength, the equation = 2 GMg r for the gravitational field strength of a point mass. (e) recall and apply the equation = 2 GMg r 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 Earth g is approximately constant and 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 GM=- r for the gravitational potential in the field of a point mass. (i) analyse 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. Nature of Science A good theory should lead to new discoveries. Newton’s theory of gravitation has enabled us to work out problems connected with space travel, leading to new knowledge about the solar system and the discovery of new planets. Relating Science and Society Explore how data from satellites is used in Singapore, making reference to the work of the Centre for Remote Imaging, Sensing and Processing (CRISP) and the Meteorological Service Singapore (MSS). Examples of how the data is used by Singapore include the monitoring of the haze problem and the prediction of the weather. By analysing satellites currently deployed around the globe, compare the functionality and purposes of various types of satellites (e.g. geostationary versus polar and low earth orbit), and weigh the costs and benefits of launching our own satellites. 60 ASMC, Regional Haze Situation. Retrieved from [http://asmc.asean.org/home/]. 61 NEA, Haze updates. Retrieved from [http://www.haze.gov.sg/haze -updates]. Name: ________________________________ ( ) Class: 25 / ___

ANDERSON SERANGOON JUNIOR COLLEGE PHYSICS 9749 7-2 Additional Notes Before 1686, much data had been collected on the motions of th