Science - Physics 2 Flashcards
1
Q
What can experiments in space help with?
A
Experiments in space can help to develop new materials and medical treatments.
2
Q
What types of matter can materials exist in?
A
Three states of matter, solid liquid and gas.
3
Q
What are solids?
A
Solids keep their shape and volume; they cannot flow and are difficult to compress.
4
Q
What are liquids?
A
Liquids keep their volume but not their shape; they can flow, take the shape of their containers and are difficult to compress. Liquids often feel wet.
5
Q
What are gases?
A
Gases can change their shape and volume; they spread out in all directions and are easy to compress. Transparent as well.
6
Q
How can we describe the properties of different states?
A
The properties of the different states can be explained using the particle theory or particle model.
7
Q
What is the particle theory or particle model?
A
This states that all matter is made up of moving particles held together by forces of attraction. The particles can be atoms or molecules.
8
Q
Tell me what a solid is using the particle theory
A
State: solid
Forces: strong
Spacing: close
Movement: vibrate in fixed positions
Regular arrangement
9
Q
Tell me what a liquid is using the particle theory
A
State: liquid
Forces: fairly strong
Spacing: close
Movement: move around within the liquid
Irregular arrangement
10
Q
Tell me what a gas is using the particle theory
A
State: gas
Forces: weak
Spacing: far apart
Movement: move about fast in all directions
Random arrangement
11
Q
Why do scientists think the particle model is correct?
A
Scientists th]ink the particle model is correct because it explains many observations.
12
Q
Diffusion using the particle model
A
Gases or liquids mix without anything moving them because the particles are moving around all the time.
13
Q
Brownian motion using the particle model
A
Tiny bits of dust in air or water can be seen jiggling around around as they are hit by the moving air or water particles
14
Q
Expanding and contracting
A
materials expand when heated and contract (get smaller) when cooled. This is because the particles in hotter materials move faster and so take up more space.
15
Q
Density changes
A
density is the mass of a certain volume of a material. When a material contracts, its density increases, because the same mass of particles takes up a smaller volume. A material’s density decreases when it expands.
16
Q
How do buildings and bridges not bend or break?
A
They have to be built with gaps in so that, if the materials in them expand, the structure does not bend or break.
17
Q
The forces of attraction between all of the states?
A
The forces of attraction between particles are strongest in a solid, and weakest in a liquid.
18
Q
What happens when we increase the temperature of particles?
A
The particles gain more energy, because of this, they start to move more faster, they start to take more space
19
Q
What is density?
A
The mass of a piece of material with a volume of 1 cm3 is the density of the material
20
Q
people wrong when people say that metals are heavier than wood, what do they actually mean?
A
They usually mean that a piece of metal will have a greater mass than the same sized piece of wood.
21
Q
What will happen if the volume of an object changes without its mass changes?
A
This usually happens when matter will be heated or cooled, the density will change.
22
Q
What can volume be measured by?
A
Metres cubed or centimetres cubed or even millimeters cubed
23
Q
Forumula for volume?
A
volume = l * w * h
24
Q
what is the formula for density
A
density = mass / volume
25
What are the units for density
the units can be kg/m3, g/cm3
26
show me the mass, density, volume triangle
Mass
Density Volume
26
Formula for volume
Mass / density
27
What is melting and freezing?
Changes of state
27
Formula for mass
mass = density * volume
28
What is sublimation and an example of it?
Some materials (including ice in some conditions) can change directly from a solid to a gas. This is called sublimation.
29
What is combusion and neutralisation and why?
Combustion and neutralization are chemical changes, because the atoms within substances become combined find different ways to form new substances.
30
What are physical changes?
Changes of state are physical changes, because the chemicals in the substances do not change.
31
What happens when you heat a substance to its melting point?
It forms a liquid
32
When can particles evaporate?
Particles can evaportate from the surface of a liquid to form a gas at any temperature.
33
What is the boiling point of a substance?
The boiling point of a substance is the temperature when evaporation happens within the liquid. The bubbles in boiling water are bubbles of water vapour.
34
What happens if you cool a gas?
It condenses into a liquid.
35
What happens if you cool a liquid?
If you cool a liquid, it starts to turn into a solid when the temperature reaches its freezing point. The freezing point and melting point of a substance are always the same temeprature.
36
Mixtures changing state?
A mixture changes state over a range of temperatures because it contains substances with different melting and boiling points.
37
Describe the energy transfers between states
Energy is needed to overcome the forces holding particles together when solids change into liquids. When a liquid turns back into a solid, this energy is no longer needed and is transferred to the surroundings. The temperature of the substance remain the same while the liquid is changing to a solid.
38
How does a solid and liquid expand
A solid expands when it is heated and it expands even further when it forms a liquid.
39
What are fluids?
Liquids and gases
40
What do particles in fluids do?
Move around in all directions.
41
What happens when paticles in fluids hit things?
The force of the particles hitting things causes pressure
42
What directions does pressure come from in fluods?
Particles in fluids come from all directions.
43
How many pascals is Atmospheric pressure?
Atmospheric pressure (the pressure of the air) at the surface of the Earth is about 100000 pascals.
44
What is 1 pascal?
1 Pascal (Pa) is a force of one newton on every square meter
45
Why do we not notice atmospheric pressure?
We do not notice this pressure because fluids inside our bodies are at a similar pressure.
46
Car and bicycle tires contain air under
high pressure
47
How is the pressure high in car and bicycle tires?
The pressure inside is high because extra air has been pumped into the tire so there are more particles to hit the inside walls of the tire.
48
As the temperature in fluids increase, the pressure ___, explain why
Pressure in fluids increase as the temperature increases, because the particles move faster and hit the walls of the container harder.
49
What happens if you decrease the volume of where a fluid is in?
If you compress the same amount of gas into a smaller volume the pressured also increases, because the particles hit the walls more often.
50
What depends the pressure in a fluid?
Pressure in a fluid depends on the weight of the fluid above.
51
Why is it as you go down into the ocean, the pressure increases?
As you go down into the ocean there is more water above you and the pressure increases.
52
Where is the surface of the Earth?
The surface of the Earth is at the bottom of the atmosphere
53
What happens to the pressure as we go up a mountain?
If we go up a mountain there is less air above us and so the pressure gets less. There are fewer particles in each metre cubed of air.
54
What happens when you are standing (in gravitational terms)
Gravity is pulling you down.
55
What were the first boats made by humans? Give the history of boats
The first boats used by humans were probably just tree trunks dug out to make canoes. Later, pieces of wood were shaped and fixed together to make ships. The first ship made out of metal was not built until 1860.
56
What force stops you from sinking into the Earth?
An upwards force from the ground
57
What do you feel while you're in water, and why (weight terms)
When you float in water, you feel that you are weightless. This is because there is a force from the water called upthrust, this pushes up against your weight.
58
How can an object float?
An object will float when the upthrust balances its weight.
59
How can you measure upthrust on an object in a fluid?
Attach a newton meter into the object using strings and let it sink, the measurement shown on the newton meter is the upthrust
60
How can you workout if something can float in a fluid?
You can work out if something will float in a fluid if you know its density and the density of the fluid.
61
What is the density of water and how can you work out if something can float in water?
The density of water is 1g/m3. If something has a density less than 1g/cm3 it will float in water. For objects that float, the greater their density the more of the object is under the water.
62
What is the density of air at sea level?
0.001 g/cm3
63
How can hot air balloons fly?
Hot air balloons fly because the overall density of the whole balloon (including the basket and the passengers and the hot air inside it) is less than the air around it. The air inside is heated to make it expand and become less dense.
64
What is drag?
Any object moving through water or air will have a resistance force on it that will slow it down. Water resistance and air resistance are types of drag.
65
Why is drag caused on a moving object?
The drag on a moving object is partly caused by friction between the moving object and the fluid. The friction can also cause the moving object to heat up.
Some of the drag is caused because of the object has to push some of the fluid out of the way. The faster the object is moving, the more fluid has to be pushed out of the way each second.
66
How can you reduce frictional drag?
This part of drag is reduced by giving the object a smooth surface
67
How can you reduce speed drag?
This part of the drag is reduced by kee[omg the area that faces the moving air or water as small as possible, and by giving the object a streamlined shape. This makes it easier for the fluid to move around it.
68
The faster the object is moving,
the greater the drag
69
A vehicle travelling at a steady speed has
balanced forces on it. A forward force from the engine is needed to balance the drag forces. If the drag is less, the vehicle will not need such a big force from the engine to travel at that speed, and it will not use up as much fuel.
70
How do astronomers explore the solar system?
Today, astronomers use spacecraft and powerful telescopes to explore and observe the Solar System.
71
What could early astronomers see?
Early astronomers could only use their eyes and so only made observations of the five planets visible from Earth without using a telescope (Mercury, Venus, Mars, Jupiter and Saturn)
72
What is Ptolemy's model of the solar system?
The Greek astronomer Ptolemy (c90-168AD) used measurements of the sky to create his geocentric model.
This model had the earth at the centre and all the planets along with the Sun orbiting around it.
73
Why did most astronomers accept Ptolemy's geocentric model?
Most astronomers accepted this model for the next 1500 years because it could explain many of their observations.
74
What is Copernicus's model of the solar system?
In 1543, an astronomer named Nicolaus Copernicus put forward a new idea.
He suggested that the Earth was not at the center of the solar system.
He argued that the Earth rotates daily on its axis and revolves yearly around the Sun, a heliocentric model.
75
Why was Copernicus's heliocentric model not accepted?
Copernicus' model was not accepted straight away, partly because it still did not explain all the observations very well. However, observations made by Galileo using one of the first telescopes provided evidence to support Copernicus' model.
76
Who was Galileo Galilei
He invented one of the first telescopes. Galileo made many observations using his very own telescope.
His observations provided more evidence to support Copernicus’ model.
This idea was still controversial at the time and not accepted by other astronomers until many years later.
77
What is the model we use today?
The model we use today was suggested by Johannes Kepler in 1609.
In this model the Sun remains in the centre of our solar system, but the planets move around the Sun in elliptical orbits. Most of the planets have moons orbiting them.
78
What are comets?
Comets are balls of dirty ice in very elliptical orbits around the Sun
79
Spacecrafts in space
Luna 2 was the first s[ace [rpbe tp reach the moon. It crashed into the Moon in 1959, later probes made soft landings and some even brought back some Moon rocks to the Earth. Before this, scientists could only investigate other planets by looking at them through telescopes.
We send space probes into space to view distant planet and send the information back to Earth.
80
What is the most distant space craft?
The most distant space craft from Earth is the Voyager 1.
It is nearly 19 billion kilometres away from the Earth.
We have used this space probe to study images from Jupiter and Saturn.
81
What are the 4 seasons?
Spring Summer Autumn Winter
82
Why do we have very different weather patterns around the world?
The weather in some parts of the world is very different at times of the year. These changes happen because the Earth's axis is tilted.
83
How is the earth divided?
The Earth dis divided into htwo halves or hemispheres by an imaginary line called the Equator. Europe, North America, part of Africa and most of Asia are in the northern hemisphere.
84
Why is the sun higher or lower in different seasons?
In summer, the Sun is high in the sky at midday and days are longer than nights. In the winter, the Sun is not very high in the sky at midday and nights are longer than days.
85
Why are shadows longer during the seasons?
During the seasons the sun's position in the sky changes, the more lower it is,the longer the shadow.
86
Why is the sun hotter in the summer than in the winter (hemisphere wise)
The Sun feels hotter in the summer than it does in the winter. Some people think that this is because the Earth is closer to the Sun in summer, but this is not true in the northern hemisphere. The northern hemisphere is slightly closer to the sun in winter. This means that the southern hemisphere is closer to the Sun during its summer, which is one reason why summers are often a little hotter in the southern hemisphere than they are in the northern hemisphere.
87
Why is the sun hotter in the summer than in the winter (sky height wise)
The sun feels hotter in summer compared with winter because it is higher in the sky. This means the heat from the Sun is more concentrated. Summer days are also warmer than winter days because the sun is shining for longer and has more time to warm up the ground.
88
What is a magnet?
A magnet can attract objects made from magnetic materials including iron, nickel and cobalt. A magnet can attract or repel another magnet. The space around a magnet where it can affect other materials is called the magnetic field.
89
How do modern ships work out where they were?
Modern ships use information from satellites and radios to work out where they are and which way to steer. Until the middle of last century, sailors had to use a compass and a map or chart to help them navigate.
90
History of magnets and how a compass works?
Magnetic materials were discovered thousands of yerars ago. It was found that pieces of rock that contained a lot of iron would always point north if they were hung from a thread. A magnet that points north can be used as a compass. When people made bar magnets, they named the end that pointed north the north-seeking pole. We call the other end of the magnet the south-seeking pole. These names are usually shortened to north pole and south pole.
91
What happens if you put two magnets together?
If you put two magnets near each other, the north pole of one magnet will attract the south pole of the other. Two north poles (or two south poles) will repel each other. Lines of force around the north and south pole join together.
92
What is a magnetic field?
The space around a magnet where it has an effect is called its magnetic field. A field in physics is a space in which a particular force has an effect. You can find the shape of a magnetic field using iron fillings or a small compass.
93
How is the shape of a magnetic field represented?
The shape of a magnetic field is represented by field lines. The direction of the field is always from the north pole of the magnet towards the south pole.
94
What determines the strength of the magnetic field?
The field is strongest where the field lines are closer together. The field gets weaker as you get further from the magnet. The field is all around the magnet.
95
Does the magnetic field have a direction?
The magnetic field has a direction. This direction is the way the north pole of a compass moves near another magnet. North poles repel each other, so the direction of the magnetic field is away from the north pole of the bar magnet and towards the south pole.
96
Order of Earth's layers
Inner core, outer core, mantle, crust.
97
Why does Earth have a magnetic field?
The outer core is liquid iron. The movement of this iron causes the earth to act like a magnet.
98
Geographic south pole =
magnetic north pole
99
What is gravity?
When any two objects are near each other they exert a tiny force that tries to pull them together. This force is called gravity. The bigger the mass of the object, the stronger the force it exerts
100
What is weight?
The force of gravity pulling on you is your weight and is measured in Newtons (N).
101
How did Earth form?
When the Earth was formed from rocky particles, the gravitational attraction between the particles pulled them all together to form a sphere.
102
What is a gravitational field, and gravitational field strength?
The space around the Earth where its gravity attracts things is the Earth's gravitational field. The gravitational field strength at the surface of the Earth is about 10 newtons per kilogram (N/kg) and is represented by the letter g italics. This means that the Earth's gravity pulls on every kilogram with a force of 10 N. The gravitational field strength is different on other bodies in the Solar system.
103
Formula for weight?
Weight (N) = mass (kg) * gravitational field strength (N/kg)
104
Why is Earth orbiting the Sun?
The Earth is moving around the Sun at approximately 100000km/h. If there were no gravity from the Sun, the Earth would fly off into space. The force of gravity between the Sun and the Earth keeps Earth in its orbit. Gravity keeps the other planets and comets in orbit around the Sun.
105
What happens to the force of gravity as objects move apart?
The force of gravity gets weaker when the two objects attracting each other get further apart.
106
What is a satellite?
Anything that orbits a planet is called a satellite.
107
What is Earth's satellite?
The Moon is a natural satellite of the Earth.
108
What are artificial satellites?
Artificial satellites are kept in orbit around the Earth byu the Earth's gravity. Their uses include photographing the Earth and transmitting TV programmes.
109
Before compasses how did people navigate?
Before compasses, people used starts to guider them. Polaris is a start that is always above the North Pole
110
What are constellations?
Constellations are patterns of starts, constellations can be used to find Polaris which lets you work out which direction is north.
111
What are stars?
Stars are huge balls of gas that give out large amounts of energy (some of which can be seen as light)
112
Why do stars we see at night seem less bright than the sun?
The stars you see at night do not seem very bright compared with the Sun because they are much further away.
113
Why cant we see other stars during the day?
We cannot see them during the day because light from them is very faint compared with light from the sun
114
what did people see when they first observed stars?
Blurred patches of light
115
what is one light year?
One light year is the distance travelled by light in 1 year. It is approximately 10000000000000 km
116
What is the nearest star to the sun?
Proxima centauri, it is 4.22 light years away. It would take a rocket from Earth over 12000 years to reach Proxima Centarui
117
