Understanding Orbital Motion
•The universal law of gravity allows us to understand orbital motion of planets and moons:
• Earth and moon attract each other through gravitation.
Example:
Earth
Moon
v
v’
Dv
F
• Since Earth is much more massive than the moon , the moon’s effect on Earth is small.
• Earth’s gravitational force constantly accelerates the moon towards Earth.
• This acceleration is constantly changing the moon’s direction of motion, holding it on its almost circular orbit.
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