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Space - Coggle Diagram
Space
Gravitational force
People often confuse mass and weight. Remember that weight is a force that acts upon a mass, and is measured in newtons, N. Mass is measured in kilograms, kg.
Mass
The mass of an object is the amount of matter or ‘stuff’ it contains. The more matter an object contains, the greater its mass. An elephant contains more matter than a mouse, so it has a greater mass.
Mass is measured in kilograms, kg. A 100 kg object has a greater mass than a 5 kg object. An object's mass stays the same wherever it is. So a 5 kg mass on Earth has a 5 kg mass on the Moon.
The force of Gravity
Gravity is a force that attracts objects towards each other. Gravity only becomes noticeable when there is a really massive object like a moon, planet or star. We are pulled down towards the ground because of gravity. The gravitational force pulls in the direction towards the centre of any object. So we are pulled towards the centre of the Earth.
Days & Nights
A planet spins on its axis as it orbits the Sun. A day is the time it takes for a planet to turn once on its axis. An Earth day is 24 hours long.
The Sun lights up one half of the Earth, and the other half is in shadow. As the Earth spins we move from shadow to light and back to shadow and so on. It is daytime in the UK when our part of the planet is lit by the Sun. And it is night in the UK when our part of the planet is facing away from the Sun.
Path of the Sun
During the day, the Sun appears to move through the sky. Remember that this happens because the Earth is spinning on its axis. In the UK, if we look south and follow the path of the Sun in the sky during the day,
The Sun appears to move from east to west. This is because the Earth turns from west to east. The Sun appears to:
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One way to remember which way the Earth turns is to remember ‘we spin’, which means that we (the Earth) spins from west to east.
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Weight
The weight of an object is the gravitational force between the object and the Earth. The weight of an object depends upon its mass and the gravitational field strength.
Gravitational field strength is given the symbol g. Do not confuse this with g for grams. You can use this equation to calculate the weight of an object:
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On Earth, g is about 10 N/kg. This means that a 2 kg object on the Earth’s surface has a weight of 20 N (2 kg × 10 N/kg = 20 N)
Mass & Weight
The mass of an object stays the same wherever it is, but its weight can change. This happens if the object goes where the gravitational field strength is different from the gravitational field strength on Earth, such as into space or another planet.
The Moon is smaller and has less mass than the Earth, so its gravitational field strength is only about one-sixth of the Earth’s. So, for example, a 120 kg astronaut weighs 1200 N on Earth but only 200 N on the Moon. Remember that their mass would still be 120 kg.
Years & Seasons
A planet's year is the time it takes to make one complete orbit around the Sun. The Earth goes once round the Sun in one Earth year, which takes 365 Earth days.
Seasons
The Earth's axis is the imaginary line through the centre of the Earth between the South and North poles about which the Earth rotates. This axis is tilted slightly compared with the way the Earth orbits the Sun.
We get different seasons (winter, spring, summer and autumn) because the Earth’s axis is tilted. This is how it works:
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