Orbital-Motion

• What must change for a stable orbit if speed changes?

  The radius of the orbit must change
• What type of orbit does the Earth follow around the Sun?

  Circular orbit
• How do planets actually orbit the Sun?

  More like an elliptical orbit
• What holds the Earth in its orbit around the Sun?

  The force of gravity
• What type of satellite is the Moon classified as?

  Natural satellite
• What holds the Moon in its orbit around the Earth?

  The force of gravity
• How often do geostationary satellites orbit the Earth?

  Once every 24 hours
• What is the key point about the force of gravity in circular orbits?

  It changes velocity but not speed
• What does velocity represent?

  Speed in a given direction
• How does the direction of an object's movement affect its velocity?

  Constantly changing direction changes velocity
• What happens to the speed of a satellite in a circular orbit?

  The speed remains constant
• What must happen if the speed of a satellite changes?

  The radius of its orbit must change
• What happens to the radius of a satellite's orbit if its speed increases?

  The radius decreases
• Why does the radius decrease when speed increases?

  Greater force of gravity is needed