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1.  1. Why is the acceleration of uniform circular motion directed toward the centre of a circle? 

 2. Using circular motion to approximate elliptical orbits, how can you describe the motion of planets, moons natural satellites and satellites artificial satellites using mathematical relationships formula.

3.  How was Newton able to use Kepler laws that described the motion of planets as elliptical orbits around the sun, to develop his law of universal gravitation?

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4.  What is the relationship between the kinetic energy due to motion the potential energy stored and the total mechanical energy of an object in a closed isolated system?

5.  What is work? 

 6. How does the mechanical energy change in a system that is not isolated?