Transcript Planetary Motion File

Bell Ringer
• What celestial body is at the center of our solar system?
• What is celestial body or bodies has the farthest orbit in
our solar system?
• What shape are the planets orbits?
• Grab a book when you finish the bell ringer questions.
PLANETARY MOTION
AND GRAVITATION
By: Mr. Schlamb
Sun Centered or Earth Centered
• Long believed the Earth was center of solar system
• Nicholas Copernicus Polish astronomer:
• Planets and stars don’t agree with Earth-centered model
• Work published in 1543 while on his deathbed
• Motion is much more easily understood with Sun at center
• Tycho Brahe did not agree with this
• Says Sun and moon orbit Earth
• All other bodies orbit the Sun
Johannes Kepler
• 3 Laws:
• The paths of the planets are ellipses with the Sun at one focus
• An imaginary line form the Sun to a planet weeps out equal areas
in equal time intervals
• This is an equation:
• First two laws apply to each planet moon and satellite individually
• The third law related the motion of several objects about a single
body: compares planets distance from Sun to their periods about
the Sun
Newton’s Law of Universal Gravitation
• Law of Universal Gravitation– objects attract other
objects with a force that is proportional to the product of
their masses and inversely proportional to the square of
the distance between them
• In short the equation is:
• The force of attraction between tow objects must be
proportional to the objects masses is known as
gravitational force
What is G?
• G stands for the universal gravitation constant
• G=
• **Note G is a constant its value never changes
Period of a Planet
• Time it takes for a planet to make one full revolution
• Period of Planet orbiting the Sun:
Exit Slip
• Using Newton’s law of universal gravitation, find the force
exerted between two objects separated by a distance of
8m. Object one has a mass of 12kg while object two has
a mass of 15kg.
• What would you like more practice with after today
lesson?
• What is one thing you would like to do more of in class?
• Is there anything you don’t understand from todays
lesson?