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Significance of Gravitational Force (view source)
Revision as of 11:21, 4 December 2013
, 11:21, 4 December 2013→Concept #
* '''Question Corner'''
* '''Question Corner'''
==Concept #==
==Concept #2 - Kepler's Laws ==
===Learning objectives===
===Learning objectives===
#The key concept to understand here is that gravitational forces play an important role in planetary motion.
#Three laws of planetary motion that describe the motion of the planets have been postulated based on detailed astronomical observations
===Notes for teachers===
===Notes for teachers===
''These are short notes that the teacher wants to share about the concept, any locally relevant information, specific instructions on what kind of methodology used and common misconceptions/mistakes.''
''These are short notes that the teacher wants to share about the concept, any locally relevant information, specific instructions on what kind of methodology used and common misconceptions/mistakes.''
<br><br>
'''Laws of Planetary Motion'''
We now know that satellites are continually falling towards the Earth following a curved path whose curvature is greater than that of the curvature of the Earth. The Moon is just such a satellite that moves around the Earth. In a similar way, all the planets that move around the Sun are satellites of the Sun. The motion described in such a situation is not strictly circular - it is elliptical.
Johannes Kepler, working with data painstakingly collected by Tycho Brahe without the aid of a telescope, developed three laws which described the motion of the planets across the sky.
<br><br>
#The Law of Orbits: All planets move in elliptical orbits, with the sun at one focus.<br><br>
#The Law of Areas: Each planet moves so that an imaginary line drawn from the Sun to the planet sweeps out equal areas in equal periods of time.<br><br>
#The Law of Periods: The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit.<br><br>
Kepler's laws were derived for orbits around the sun, but they apply to satellite orbits as well. For details of Kepler's laws click [http://karnatakaeducation.org.in/KOER/en/index.php/Kepler's_Laws here]. <br><br>
===Activity No # ===
===Activity No # ===
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