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science - Coggle Diagram
science
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Lots of materials are solid, such as paper, bricks, wood, metal, and ice.
The particles in solids are very close together, therefore they cannot usually be compressed or squashed. Forces of attraction between the particles hold them together and keep them in place.
The particles in solids are arranged in a regular way. The particles in solids move only by vibrating about a fixed position. This gives solids a fixed shape and means that they cannot flow like liquids.
The hotter a solid gets, the faster its particles vibrate. This means that solids expand when they are heated.
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When substances are heated and expand, their particles do not get any bigger.
When heated, the particles begin to vibrate more which causes them to move slightly further apart.
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By looking around, how many examples of solids can you see, touch, hear or feel?
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There are many different liquids such as; water, oil, fruit juice, and many others.
The particles in liquids are arranged in a random way, and are close together, touching many of their neighbours. There are some gaps, but liquids cannot usually be compressed or squashed.
The particles of a liquid have enough energy to break free of some of the forces of attraction between the particles. So particles in liquids can move around and can move over each other, allowing liquids to flow and be poured.
Circles randomly spaced close to each other, representing a particle model of a liquid
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In a diagram of the particles in a liquid, make sure that they are mostly touching but randomly arranged.
If there are large spaces between the particles, you would be able to compress the liquid.
Sand can be poured, but it is definitely a solid. Why is this?
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There are lots of different gases, such as the air we breathe or the helium used to fill balloons.
The particles in gases are widely spaced and randomly arranged, meaning they can be easily compressed or squashed.
The particles in a gas have enough energy to overcome the forces of attraction between the particles, so are free to move in any direction. They move quickly in straight lines, colliding with each other and the walls of their container.
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There are large spaces between the particles of a gas. These spaces between particles are empty, there is nothing in them.
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A distance-time graph is a useful way to represent the motion of an object. It shows how the distance moved from a starting point changes over time.
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A graph plotting distance travelled by time taken with a line increasing upwards from point a to b, c ,d and finally e where the line tapers off and stays constant.
At a, the object is travelling at a constant speed, so it is shown with a straight diagonal line, where the gradient of the line tells you the speed.
At b, the object is accelerating so it is shown with a curved line which gets steeper.
At c, the object is travelling at a constant speed again, but this time it is faster, so the straight line is steeper - it has a larger gradient.
At d, the object is decelerating, so line is curved and gets less steep.
At e, the object is stationary, so its distance does not change as the time taken increases. This means that for a stationary object, the line is flat and the gradient (the speed) is zero.
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Show the forces acting on an object in a free body diagram. The arrows represent the size and direction of the forces acting.
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A force meter, also known as a newton meter, can be used to measure the size of a force.
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It is important to ‘zero’ the force meter before you use it. This means adjusting it so that the reading is zero when there is no force acting on it.
If you don’t ‘zero’ the force meter, all your measurements will be inaccurate by the same amount. This is called a systematic error.
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When an object pushes on a surface like a table, wall or the ground, the surface pushes back on the object with a balancing force.
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In the diagram, Earth pulls the satellite and the satellite pulls Earth. The forces are equal in size and opposite in direction.
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There are many examples of where friction is a useful force. For example, friction is why we do not slip when we walk along the pavement. It is also useful in bikes and cars. Without friction, they would not be able to accelerate, turn or brake.
Friction can also be unhelpful. For example when the mechanical parts of a bike, like the chain and axles, rub together the friction can cause the metal to wear away.
Friction also causes objects to heat up. For example, rubbing hands together on a cold day to keep warm. The friction between the palms of your hands causes them to heat up. Friction between moving objects causes thermal energy to be dissipated out to the surroundings.
We can limit the amount of friction using lubrication. Substances like motor oil can be used to stop metal parts from rubbing and wearing away.
Modern taps use moving parts made from a low friction plastic called PTFE, rather than rubber and brass.
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