KS3 physics revision Flashcards
Describe the particles in a solid.
Solids are in a fixed position and vibrate but do not move they are also in a uniform formation.
Describe the particles in a liquid.
Liquids are close together in a non uniform arrangement and can move slightly.
Describe the particles in a gas.
Gases are far apart and move in a quick way it is in a non uniform formation.
What happens as particles gain energy- why do materials expand when heated?
When a solid is heated, its atoms vibrate faster about their fixed points. Liquids expand for the same reason, but because the bonds between separate molecules are usually less tight they expand more than solids. Heat causes the in gases molecules to move faster, (heat energy is converted to kinetic energy) which means that the volume of a gas increases more than the volume of a solid or liquid.
How is the arrangement of particles linked to the density of materials?
Density is amount of material substance in kg divided by the space the substance occupies in cubic metres. The constituent atoms plus how densely they are or are not packed determines both mass and volume. For example, gold consists of “weighty” atoms, packed closely together in a very efficient packing pattern, so gold is dense
How do you calculate density?
Mass/volume=density
Explain why a hot air balloon rises in the air
Because hotter air is less dense than colder air, heating the air in the balloon makes the balloon rise, while allowing the air in the balloon to cool makes the balloon fall.
Explain why some materials float in water whilst others sink
Objects that are more dense than water sink and those less dense float. Objects such as a life jacket will also float because it is hollow with air which is less dense than water.
What are the units of pressure?
Pascal
Use ideas about particles to explain how (and why) pressure changes in fluids as you go deeper in an ocean or higher up a mountain.
The deeper you go into the ocean the more particles will be on top of you as there will be atmospheric pressure of the water pushing down on you. This is similar to if you are high up a mountain however it is the opposite as the further up you travel there is less air above you therefore less particles.
Use ideas about particles to explain how (and why) pressure changes in fluids as you go deeper in an ocean.
The deeper you go into the ocean the more particles will be on top of you as there will be atmospheric pressure of the water pushing down on you.
Use ideas about particles to explain how (and why) pressure changes in fluids as you go higher up a mountain.
Being deep in the ocean is similar to if you are high up a mountain however it is the opposite as the further up you travel there is less air above you therefore less particles and less atmospheric pressure. Humans struggle to get enough air at such a low air pressure which is why it is more difficult to breath at a higher altitude.
Find out about the collapsing can experiment. Explain in terms of particles and pressure why this happens
To make the can collapse you take some water and fill the can slightly before placing over a Bunsen burner. Next the water will start to boil and will force the air out of the can and will replace it with water vapour. Finally if you turn the can upside down and place it in a trough of water it will cause the water vapour to condense and the pressure decreasing. Usually the air pressure inside the can is the same as outside the can, but now the inside of the can has changed and the outside hasn’t it will collapse.
How does a difference in pressure enable you to breathe or drink through a straw?
When you suck air from the straw, less air pushes on the water inside the straw than on the water outside of it. This imbalance causes more water to be pushed into the straw. The water will rise until the pressure created by the water column in the straw equals the air pressure difference.
Describe changes in day length at different points around the Earth
The length of a day changes far more during the year at higher latitudes than at lower latitudes. (Latitudes beyond 66°33′ are not shown because the Sun does not always rise or set at these latitudes.) The graph runs from one winter solstice to the next, with the two equinoxes clearly visible in March and September.
How does the tilt of the earth cause seasons?
Earth has seasons because its axis is tilted. Earth’s axis is always pointed in the same direction, so different parts of Earth get the Sun’s direct rays throughout the year. For example, in summer, the Sun’s rays hit that region more directly than at any other time of the year.
List the 8 planets in order
Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
How does orbit time change as planets get further from the Sun?
The planets further away from the sun not only has a longer path but also move more gradually due to the lower gravitational pull from the sun. This means that the further the planet is away from the sun the longer the orbit time is.
What does ‘natural satellite’ mean?
A natural satellite is any celestial body in space that orbits around a larger body. Moons are called natural satellites because they orbit planets
What is a comet’s orbit?
Comets go around the Sun in a highly elliptical orbit. They can spend hundreds and thousands of years out in the depths of the solar system before they return to Sun at their perihelion. Like all orbiting bodies, comets follow Kepler’s Laws - the closer they are to the Sun, the faster they move.
What is an asteroid’s orbit?
Asteroids are small, rocky objects that orbit the Sun. Although asteroids orbit the Sun like planets, they are much smaller than planets. There are lots of asteroids in our solar system. Most of them live in the main asteroid belt—a region between the orbits of Mars and Jupiter.
What is a moon’s orbit?
The moon orbits the Earth once every 27.322 days. It also takes approximately 27 days for the moon to rotate once on its axis. As a result, the moon does not seem to be spinning but appears to observers from Earth to be keeping almost perfectly still. Scientists call this synchronous rotation.
What galaxy contains the solar system?
The milky way
What is a light year? (definition)
a unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 million million miles).
