We will divide Physics into 3 sections and 13 chapters:
UNIT 1 (Chap. 1-5)
1. Measurement and Units
2. Area, Volume, Density, Speed, Velocity and Acceleration
3. Force and Work
4. Moments and Center of Gravity
5. Pressure
UNIT 2 (Chap. 6-9)
6. Energy
7. Heat
8. Light
9. Sound
UNIT 3 (Chap. 10-13)
10. Magnetism
11. Static Electricity
12. Current Electricity
13. Electricity in the House and Electronics
Unit 1.
1. Measurement and Units
2. Area, Volume, Density, Speed, Velocity and Acceleration
3. Force and Work
4. Moments and Center of Gravity
5. Pressure
1. Measurement and Units
2. Area, Volume, Density, Speed, Velocity and Acceleration
3. Force and Work
4. Moments and Center of Gravity
5. Pressure
Chapter 1. Measurement and Units
Length is measure in meters (m)
A kilometer (km) is 1000 meters
A centimeter (cm) is 0.01 meters
A millimeter (mm) is 0.001 meters
A kilometer (km) is 1000 meters
A centimeter (cm) is 0.01 meters
A millimeter (mm) is 0.001 meters
Chapter 2: Area, Volume, Density, Speed, Velocity, Acceleration
Area
Volume
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Density
- Find the volume using the overflow can - Divide the mass by the volume -Flotation occurs when the object is less dense than the liquid
Speed
Velocity
Acceleration
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Chapter 3: Force and Work
- A force is something that cause an object to move or change shape
- The weight of an object is the force of gravity acting on it
- friction is something which opposes motion
- Advantages = Brakes
- Disadvantages = Waste of energy, wears away surfaces
- Oil is a lubricant used to reduce friction
- Hooke's law: The extension of a spring is directly proportional to the force causing it
Chapter 4: Moments and centre of gravity
- The turning effect can be increased by a stronger force or distance from the fulcrum
- Moment of force = Force × perpendicular distance to the fulcrum
- A lever is any rigid body free to turn about a fixed point called a fulcrum
- Law of the Lever = When a lever is balanced by any sum of moments on the left equal the sum of the moments on the right
- The centre of gravity is the point where all its weight appears to act
- Stability can be increased in two ways:
- Wide base
Chapter 5. Pressure
What is Pressure??
- The Weight of an object on a surface.
- By definition (Force per unit area) or (Pressure = Force over Area)
- It is gotten by a unit of a force N (Newtons) and dividing it by a unit of area cm^2 (centimeters squared) or m^2 (meters squared)
- The unit of pressure is the Pa (pascal) or N/m^2 (newton per meter squared)
- The pressure can be increased by:
- Increasing the force (more Newtons)
- Decreasing the area that the force is acting on (Less cm^2/m^2)
Pressure in Liquids
In a liquid, pressure gets greater the deeper you go, because there is more water on top of you. This squeezes you down.
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Atmospheric pressure (Air Pressure)
The air is also like the Liquids, lying on top of us. this also creates pressure on our bodies. The Higher up you go the lower the pressure gets. Because less air is above you.
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Measuring Atmospheric Pressure
- Atmospheric pressure is measured with a Barometer.
- A barometer can also be used as as Altimeter which tells us the height above sea level.
- Atmospheric pressure is measured in hPa (Hectopascals)
- Normal atmospheric pressure is 1013hPa or 73cm of Mercury
Atmospheric Pressure and Weather
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Low Pressure:
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High Pressure:
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Everyday Applications of Pressure
- Flight: An airplane flies because of the difference in pressure above and below the wing. This is because the curve at the top of the wing means that air must speed up above the wing. this causes less pressure and the higher pressure below the wing lifts the plane.
Chapter 6. Energy
- Energy is the ability to do work or move something
- Energy is measured in J (Joules)
- Energy has no mass, we can't see or touch it.
- Energy can't be created or destroyed. Is just changes or spreads.
Forms of Energy
There are many types of energy. they are divided to stored energy and energy in action.
There are many types of energy. they are divided to stored energy and energy in action.
Stored Energy
This is energy that is not in action right now, but is ready to act.
This is energy that is not in action right now, but is ready to act.
Potential Energy.
An object is ready to move because of its shape or position.
An object is ready to move because of its shape or position.
- Springs
- stretched elastic bands
- Water behind a dam
Nuclear Energy
The Nucleus of an atom also stores a huge amount of potential energy. this is nuclear energy.
The Nucleus of an atom also stores a huge amount of potential energy. this is nuclear energy.
- Nuclear Bombs
- Nuclear Reactors
- The sun
Chemical energy.
Food and Fuels store chemical energy.
Food and Fuels store chemical energy.
- Food. Our bodies combine food and oxygen to keep us warm 37*C.
- Petrol, oil, gas, coal.
- Batteries.
Energy in Action
Sources of Energy
The Sun
- Our Primary source of energy.
- Plants make food from sun light in photosynthesis
- Gives off light so we can see
- Gives off heat
- Uneven heating of the earth gives us winds for Wind Energy.
- Heats water which evaporates and we get rain in rivers for Hydroelectricity.
- Powers Solar Panels.
Fossil Fuels
- When animals and plants die. The chemical energy from their remains is squashed by the ground.
- This created either Oil, Peat, Coal, Gas.
- In Ireland this is our main source of energy.
- Fossil Fuels are Non-renewable, which means they'll run out.
- The burning of fossil fuels gives off greenhouse gasses like CO2 (Carbon Dioxide).
Renewable Energy Sources
- This is energy that will not run out.
- These make no harmful waste products
- They are Expensive to set up.
- Examples are Solar, Wind, Hydroelectric, Wave, Tidal, Biomass and Geothermal Energy.
Nuclear Energy
- Nuclear Fission.
- Nuclear energy is made in Nuclear Reactors.
- Its made by splitting a large nucleus into two almost equal nuclei.
- 1kg of uranium makes as much energy as 3,000,000kg of coal.
- The substances used for this process are Radioactive.
- Radiation is very dangerous, it kills cells and can cause cancer.
- Nuclear Fusion.
- Here 2 small nuclei are forced to join together.
- This is what happens on the sun.
Other Sources
- Scientists are looking for new energy sources.
- Hydrogen
- Use for space travel.
- Car Manufacturers are developing hydrogen powered cars.
Ireland's Energy Needs
Ireland is mostly dependent on Fossil fuels as its energy source. This is bad as fuel prices rise. We need to find alternative energy sources.
Ireland is mostly dependent on Fossil fuels as its energy source. This is bad as fuel prices rise. We need to find alternative energy sources.
Advantages and Disadvantages of different energy sources
Fossil Fuels
- Coal, Oil, Turf, Peat, gas
- Originally sun's energy
- Advantages:
- Electricity supply guaranteed as long as fuel is there.
- Can be stored.
- Relatively cheep.
- Disadvantages:
- Limited supply available.
- Prices rise as less is available.
- Pollutes air, causes acid rain.
Solar Energy
- Sun's energy.
- Advantages:
- Supply won't run out.
- No pollution.
- Can be put on the roof not interfering with with anything..
- Disadvantages:
- Expensive.
- Less energy is produced in winter.
- No energy is produced at night.
Wind Energy
- Sun's energy
- Advantages:
- Supply won't run out.
- No Pollution.
- can be placed on farm land.
- Getting cheaper.
- Disadvantages:
- Windy sites are essential.
- Can be noisy and unreliable .
- Many turbines are needed to produce as much energy as a power station.
Hydroelectric Energy
- Sun's Energy
- Advantages:
- Won't run out
- No Pollution
- Can be switched on when needed.
- Disadvantages:
- Small number of suitable sites.
- Expensive.
- Land gets flooded.
Wave Energy
- Sun's energy.
- Advantages:
- Supply won't run out.
- No pollution.
- Huge amounts of energy available.
- Disadvantages:
- Supply varies with wind.
- Turbines at sea can be ugly (Visual Pollution)
- Huge amounts of floats would be needed to make as much energy as an average power station.
- High maintenance cost.
Tidal Energy
- Sun's and Moon's energy.
- Advantages:
- Very Reliable.
- won't run out.
- Can act as a bridge across and estuary.
- Cost of each unit of energy is lower than average.
- Disadvantages:
- Damages the estuary habitat.
- Electricity only produced at certain times during the day.
- Very expensive.
- Considering it's cost and size, it doesn't produce too much energy.
Biomass
- Sun's energy
- Advantages:
- Won't run out.
- Reduction of greenhouse gas emissions.
- Creates employment, great for poor countries.
- Disadvantages:
- Large ares of land needed.
- Can cause pollution.
- Smelly.
Geothermal Energy
- Earth's energy.
- Advantages:
- Supply free.
- Unlikely to run out.
- No pollution.
- Extremely low cost.
- Disadvantages:
- Limited number of suitable sites.
- Can be expensive to drill into the earth.
- Possible damage to the earths crust.
Nuclear Energy
- Energy from the nuclei of atoms (splitting = Fission, Fusion = Joining)
- Advantages:
- Huge amount of energy form just a small amount of of fuel.
- No harmful gasses are produced.
- Nuclear radiation has many benefits including Medical, industrial and food preservation.
- Disadvantages:
- Fission is non-renewable, uranium and plutonium will run out.
- Radioactive waste is difficult to store safely.
- Chance of a serious accident (Chernobyl, Fukushima)
Which energy source is best?
Different energy sources are suitable for different parts of the world.
Different energy sources are suitable for different parts of the world.
- Deserts are good for solar energy.
- Hot, rainy, tropical countries are good for biomass.
- countries with a lot of volcanic activity are good for geothermal energy.
- In Ireland, wind energy is best because of our strong winds.
Conserving Energy
In order to save energy we need to conserve it. without noticing we loose a huge amount of energy in our homes.
we can save energy by doing the following:
In order to save energy we need to conserve it. without noticing we loose a huge amount of energy in our homes.
we can save energy by doing the following:
- Putting lagging jackets on hot water tanks.
- Insulate attics with polystyrene or fiberglass.
- Use draught excluders on doors and windows.
- Walls should have air cavities.
- Double glazed windows.
- Use thick carpets and curtains.
- Don't open windows when it's cold outside (shocker)
- Don't heat the house when it's hot outside.
Energy conversions
Energy changes from one for to another (energy conversion or energy transfer)
Here are some Examples of energy conversions:
Energy changes from one for to another (energy conversion or energy transfer)
Here are some Examples of energy conversions:
Chapter 7 -Heat
- The unit of heat is the joule ( J )
- Temperature is the measure of the hotness of a body
- Heat is a form of energy
Objects get bigger when heated and get smaller when cooled
- Below is a metal ball and ring
- When the ball is cool , it can fit through the ring easily
- When the ball is heated , it cannot fit through the ring anymore
Air also expands when heated
- as the air is heated the water bubbles proving that heat makes air expand
Water also expands when heated
- As the temperature of the water increases the level of the water in the glass tube increases
Water acts strangely at 4 degrees
melting point of ice = 0 degrees
boiling point of water = 100 degrees
Effects of pressure on water
Latent heat
An example of how latent heat looks on a graph
note: at 4 mins - 6 mins there is no change or drop in temperature this is because there is a change in state occuring
- If you heat water above 4 degrees it expands
- If you cool water below 4 degrees it expands
melting point of ice = 0 degrees
boiling point of water = 100 degrees
Effects of pressure on water
- low pressure = lowers boiling point
- high pressure = increase boiling point
Latent heat
- this is where a change of state is happening but not a change in temperature
An example of how latent heat looks on a graph
note: at 4 mins - 6 mins there is no change or drop in temperature this is because there is a change in state occuring
Chapter 8 - Light
Light is a form of energy.
We know this because:
Light is a form of energy.
We know this because:
- Light can cause movement (Do work). Eg. Crooks Radiometer.
- Solar cells convert light energy to electrical energy.
- Green Plants convert light energy to chemical energy (food) in Photosynthesis.
- Nuclear energy is converted to light energy on the sun.
- chemical energy is changed to light energy in oil lamps, candles, fires, fireworks....
Light transmissions and sources.
The Sun
- Light travels to earth from the sun.
- It takes about 8.5 minutes for light to get to earth from the sun.
- It passes through space and through the atmosphere which is transparent.
Luminous Objects
- Luminous objects make light,
- The sun is our main luminous source of light.
- Other luminous objects include TVs, light bulbs, Fires, candles, fireworks....
Non-Luminous Objects
- Most objects we see don't give off their own light.
- They simply reflect light from luminous objects
- Some examples include the moon, planets, grass, trees, people.
Shadows
- Some objects allow light through. glass, water, diamonds.
- Most objects don't allow light through. they are sad to be opaque. Moon, person, tree, rock.
- These objects stop light and either absorb it or reflect it.
- This causes a shadow at the opposite side of the object.
Eclipses
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Reflection of Light
- When light hits something and bounces off, its called reflection.
- Reflection is the bouncing of light from a surface.
- Most surfaces have microscopic lumps and bumps (wood, paper, skin, unpolished metals) this means that light will go all over the place.
Periscopes
Applications of Reflection
- We can see things that don't give off light themselves.
- Periscopes.
- Microscopes use mirrors to direct light at the slide.
- Mirrors are placed in headlights.
- Mirrors in cars for safety.
- Make-up and shaving mirrors so we can look Fabulous
Refraction of light.
- Light doesn't always travel in straight lines.
- If it moves from one substance to another substance (With a different density) it bends.
- Refraction is the bending of light as it passes from one medium to another.
Lenses
- A lens is a piece of glass or other transparent surface that hes at least one curve.
- Lenses are used for a wide range of optical instruments like glasses, contact lenses, magnifying lasses...
Dispersion (Is white Light Really White?)
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Applications of Refraction
- Refraction is used in lenses. which are used in glasses, contacts, microscopes, telescopes, cameras...
- On a hot day refraction can cause a mirage of water on a road.
- Colours in a Diamond, Jewelry and a rainbow are caused by the dispersion and refraction of light.
- We get an extra 4 hours of sunlight in the morning before the sun comes up. This is because of refraction in the atmosphere.
Chapter 9 - Sound
- sound is a form of energy.
- it's caused by vibrations in particles.
- Sound is a form of energy caused by vibrations.
- Sound travels when particles vibrate and the vibrations are passed on to the particles besides them.
- We hear when the vibrations in the particles in the air make our eardrums vibrate.
- Sound travels at 340m/s in the AIR.
- Sound travels faster in denser materials like metals or water.
Echos
- Echos are sounds that reflect from a surface.
- Soft surfaces are good absorbers of echos. carpets, curtains.
- Ships use echos for echo-sounding or echo-location to find the depth of the sea.
- The speed of sound in water is 1500m/s.
- Ships see how long it takes for a sound to reach the bottom of the sea from the ship. they then know how deep the sea is.
Sound Levels
- Sound levels are measured using the Decibel Scale.
- The unit of sound is Decibels (dB)
- The higher the number of decibels the louder the sound is.
- Decibels are measured with a Sound Level Meter.
Chapter 10 - Magnetism
- A magnet is a piece of metal that can attract other substances to it
- The only elements that can be magnetised are iron, nickel and cobalt
- Like poles repel --- Unlike poles attract
- Magnetic field is the space around a magnet over which it has a magnetic effect
- A compass is a magnet which is free to rotate and indicate direction
- An electromagnet is an iron rod surrounded by coil wire.
- When a current flows through it is a magnet.
- Uses of magnets = Compasses, NMR Scans and moving scrap iron
Chapter 11 - Static Electricity
- Some materials when rubbed against other materials loose or gain electrons.
- An example of that would be a balloon rubbed against hair or a biro rubbed against wool.
- These materials then attract oppositely charged materials.
- This that something with more electrons (-) than protons (+) will attract something that has more protons (+) than electrons (-)
- If 2 objects both have more electrons or protons, they'll repel.
Effects of Static Electricity
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Useful Effects of Static Electricity
Harmful Effects of Static Electricity
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Earthing