Zusammenfassung der Ressource
P5a - Satellites, Gravity and Circular motion
- satellites
- an objects that orbits
a larger object in
space
- natural, e.g.
the Moon
orbits Earth
- artificial, e.g.
have been put in
space by humans
- kept in orbit by
gravitational force
- Gravity: universal force of attraction
between masses - keeps planets orbiting
the Sun and satellites orbiting the Earth
- centripetal force
- the force that acts towards the
centre of a circle that keeps an
object moving in a circle
- gravity provides the centripetal
force to keep a satellite in orbit
- gravitational force between 2 objects gets weaker as they get further apart.
- planets further away from the sun experience a lower
gravitational force and have a longer orbital period.
- different orbits
- low polar orbit satellites
- used to look at
Earth's surface
- have to be low enough and orbit
over the poles so they can see
Earth segment by segment
- each orbit = about
100 minutes
- uses: imaging Earth's
surface; weather forecasting;
military uses - spying
- geostationary satellites
- each orbit = 24 hours
- remain in a fixed position above
Earth at all times
- orbit much higher
above Earth
- uses:
communications;
satellite TV;
weather
forecasting
- artificial satellites
- can orbit at different heights above
Earth's surface
- orbital period is longer if the satellite
is at a higher position above Earth
- comets
- orbit the sun in an
elliptical loop
- when close to the sun, it has to travel fast to escape the gravitational force
BUT when far away, it travels slowly as the sun's gravity pulls it back