Starter quiz
- What happens when the Earth orbits the Sun?
- the Earth spins on its axis so it faces the Sun once each day
- the Earth moves in a circular path around the Sun once each year ✓
- the Sun moves in a circular path around Earth once each day
- the Sun moves in a circular path around Earth once each year
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- Which of the following objects orbit Earth?
- the Moon ✓
- the Sun
- stars
- the International Space Station ✓
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- Which of the following objects orbit only the Sun?
- asteroids ✓
- dwarf planets ✓
- stars
- the moons of Jupiter
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- Starting with the planet with the fewest moons, sort the following planets into increasing order of number of moons.
- 1⇔Mercury
- 2⇔Earth
- 3⇔Mars
- 4⇔Jupiter
- How many artificial satellites orbit Earth?
- fewer than ten
- about a hundred
- about a thousand
- more than ten thousand ✓
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- Starting with the planet that takes the shortest amount of time, sort the following planets into increasing order of how long they take to orbit the Sun.
- 1⇔Mercury
- 2⇔Venus
- 3⇔Earth
- 4⇔Mars
- 5⇔Jupiter
- 6⇔Saturn
Exit quiz
- Titan is a large moon of Saturn. Which of the following statements most accurately describes Titan?
- Titan is a natural satellite of the Sun.
- Titan is a natural satellite of Saturn. ✓
- Titan is an artificial satellite of Saturn.
- Titan is a planet in orbit around Saturn.
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- Which of the following types of satellites are often found in low Earth orbits?
- the Moon
- communication satellites
- observation satellites ✓
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- Why are communication satellites usually placed in a circular orbit of 35 785 km above the Equator?
- so they don't collide with the Moon
- so they remain above one point on Earth's surface ✓
- so they move across the whole of Earth each day
- so they can send signals directly to every country on Earth
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- What force acts on a satellite in geostationary orbit?
- frictional force
- gravitational force ✓
- thrust
- buoyancy
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- Starting with the satellite that has the fastest orbit, sort the following satellites of Earth into increasing order of how long they take to orbit Earth.
- 1⇔a weather satellite in a low Earth orbit
- 2⇔a communications satellite in a geostationary orbit
- 3⇔the Moon
- A satellite in low Earth orbit has an orbital radius of 8000 km and is travelling at a speed of 25 000 km/h. How many times does it orbit Earth in 24 hours?
- '12' ✓
Worksheet
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Presentation
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Video
Lesson Details
Key learning points
- Artificial satellites orbit Earth because of the gravitational attraction between them.
- The speed of a satellite along its orbit around Earth is constant.
- The velocity of a satellite along its orbit around Earth constantly changes as it changes direction.
- The centripetal force on a satellite makes it accelerate and change direction, but not speed.
- To orbit in a stable orbit, the orbital radius of a satellite must change if its speed changes.
Common misconception
Motion is always in the direction of the force acting on an object.
Provide pupils with opportunity to experience a radial force changing the direction of a small object in order to make it move in a circular path.
Keywords
Satellite - an object which orbits a planet; satellites can be natural (moons) or artificial
Polar orbit - an orbit in which the satellite passes over the poles of a planet
Geostationary orbit - an orbit in which the satellite is stationary in the sky as it orbits in the same time as the planet, directly above its equator
Orbital path - the path a satellite takes around the planet it orbits
Orbital radius - the radius of an orbit, measured from the centre of a planet
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