After this lesson, you should be able to:

• State Newton’s law of universal gravitation
• Understand the concept action-at-a-distance
• Distinguish between mass and weight
• Describe weight as a gravitational force
• Calculate the acceleration due to gravity
• Apply Newton’s law of universal gravitation to calculate the force between two masses
• Relate Newton’s gravitational law to orbital motion
• Understand the notion of apparent weightlessness