What is the sun?
A star that formed billions of years ago from clouds of dust and gas pulled together
by gravitational attraction.
What are planets?
A planet is an object in orbit around a star
What are moons?
A body in orbit around a planet.
What are comets?
Frozen rocks that move around the sun in orbits that are elliptical in shape. These
elliptical orbits take them far away from the Sun. You only see them when they return
near the Sun because then they heat up so much that they emit light.
What are meteors?
Meteors or shooting star are small bits of rocks that burn up when they enter the
Earth’s atmosphere.
What are minor (dwarf) planets?
A dwarf planet,like Pluto, has one important difference from a planet. Dwarf planets
have not cleared their orbit of other objects. In Pluto’s case there are many other
bodies of comparable size close to its orbit.
What are asteroids?
Asteroids are objects to small and uneven to be planets, usually in near-circular orbits
around the Sun and without the ice present in comets.
What is the main sequence of a star?
The main sequence is the life stage of a star during which it radiates energy due to fusion of hydrogen nuclei in its core
What is a protostar?
The concentration of dust clouds and gas in space that forms a star.
What is a neutron star?
The highly compressed core of a massive star that remains after a supernova explosion
What is a red giant?
A star that has expanded and cooled, resulting in it becoming red and much larger and cooler than it was before
What is a red supergiant?
A star much more massive than the sun will swell out after the main sequence stage to become a red supergiant before it collapses.
What is a supernova?
The explosion of a massive star after fusion in its core ceases and the matter surrounding its core collapses onto the core and rebounds in an explosion
What is a white dwarf?
A star that has collapsed from the red giant stage to become much hotter and denser
What is a white dwarf?
A star that has collapsed from the red giant stage to become much hotter and denser
Explain the life cycle of a low-mass star.
• The star initially forms from a cloud of dust and gas known as a nebula
• Gravitational attraction pulls the dust and gas closer together to form a protostar
• When the protostar becomes dense enough, hydrogen fusion begins releasing large amounts of energy
• The outward pressure of nuclear fusion outwards balances the force of gravity inwards. This is known as a main sequence star
• As hydrogen begins to run out, the “main sequence” stage ends. The outer layers of the star swells into a red giant, it becomes red as the surface cools. However, the core continues to contract. Therefore fusion of helium and other elements occur.
This means heavier elements (up to iron) are created in the core of a star
•When fusion stops no more radiation is released and the star ejects its outer layer of dust and gas, leaving a hot, dense solid core known as a White Dwarf Star
• As a white dwarf cools, it emits less and less energy. When it not longer emits a signifigant amount, it is called a black dwarf
Explain the life cycle of a high-mass star.
• The star initially forms from a cloud of dust and gas known as a nebula
• Gravitational attraction pulls the dust and gas closer together to form a protostar
• When the protostar becomes dense enough, hydrogen fusion begins releasing large amounts of energy
•The outward pressure of nuclear fusion outwards balances the force of gravity inwards. This is known as a main sequence star
• As hydrogen begins to run out, the “main sequence” stage ends. The outer layers of the star swells into a red supergiant, it becomes red as the surface cools. However, the core continues to contract. Therefore fusion of helium and other elements occur.
This means heavier elements (up to iron) are created in the core of a star
• The star contracts and expands several times before exploding in a supernova, forming elements heavier than iron and ejecting them into the universe to form new planets and stars.
• The exploding supernova throws the outer layers of dust and gas into space, leaving a very dense core called a neutron star, this is an extremely dense object made only of neutrons. However, if the star is massive enough, it will become a black hole instead of a neutron star, this is a super dense point in space with such a strong gravitational attraction that not even light can escape it
How are elements up to iron formed?
Nuclear fusion in the core of a red giant / red supergiant
How are elements larger than iron formed?
Heavy elements larger than iron are formed during a supernova explosion. The enormous force of the collapse fuses small nucle into nuclei bigger than iron nuclei. The explosion also scatters the elements throughout the universe
What is a satellite?
A satellite is anything that orbits a celestial body (star, planet, moon etc). Both natural and artificial satellites exist.
What are the uses of artificial satellites?
• Communication
• Photography
• Navigation
• Experimentation
• Weather Predictions
What are the 2 types of orbit?
- Circular orbit.
- Elliptical orbit.
What causes objects to orbit other bodies?
Objects orbit much larger bodies due to the force of gravity. The gravitational pull of the large body on the smaller object keeps it in orbit.
Why does an object in orbit not fall into a larger body?
The centripetal force of gravity accelerates the object towards the centre of the larger body, however the velocity of the object is at a right angle to the centripetal force, therefore the force of gravity only changes its direction, keeping it orbiting the larger body.
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P1 - Conservation and Dissipation of Energy34
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P2 - Energy Transfer by Conduction31
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P3 - Energy Resources62
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P4 - Electrical Circuits46
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P5 - Electricity in the Home38
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P6 - Molecules and Matter35
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P7 - Radioactivity54
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P8 - Forces In Balance46
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P9 - Motion9
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P10 - Forces and Motion29
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P11 - Pressure and Surfaces13
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P12 - Wave Properties44
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P13 - EM Waves43
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P14 - Light27
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P15 - Magnetic Fields46
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P16 - Space42
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Physics Equations24
