Physics EOY Year 9

Conservation of Energy

The law that energy can be transferred, stored or

dissipated but never created or destroyed.

Kinetic Energy

the energy an object has due to its motion

Thermal Energy

Heat/Internal energy store. The hotter it is the more it has.

Chemical Energy

Energy that can be released from a chemical reaction

gravitational potential energy

Energy stored by objects due to their position above Earth's surface.

Elastic Potential Energy

the potential energy of an object that is stretched or compressed

Electrostatic Energy

Anything electrical that is reacting with another electric charge.

Magnetic Energy

Anything magnetic that is interacting with another magnet

Nuclear energy

Energy stored in the nucleus of an atom

Open System

A system in which matter/energy can enter or leave to the surroundings.

Closed system

A system in which no matter/energy is allowed to enter or leave

Energy can be transferred

Mechanically, electrically, by heating, by radiation

Specific Heat Capacity

The amount of energy needed to raise the temperature of 1kg of a substance by 1°C

kinetic potential energy formula

Ek=1/2mv^2 or kinetic energy (J) =0.5 mass (kg) speed² (m/s)

gravitational potential energy formula

Ep=mgh or G.P.E(J) = mass(kg) x gravitational field strength (N/kg) x height (m)

Elastic Potential Energy formula

E=1/2ke² or E.P.E(J) = 0.5 x spring constant(N/m) x extension²(m)

Specific Heat Capacity Formula

∆E=mc∆θ or change in thermal energy (J) = mass (kg) specific heat capacity (J/kgC) temperature change (C)

Power

The rate at which energy is transferred, or at which work is done

Power formula work done

p=w/t or

power (W) = work done (J) /time (s)

Power formula energy transferred

P=E/T or power (W) = Energy Transferred (J) /time (s)

Conduction

Process in which particles transfer energy to neighbouring particles via vibrating.

• Energy transferred through solid

• Measures thermal conductivity how quick energy is transferred through material in this way

• Hotter particles more energy so collide passing energy between kinetic energy stores

Convection

Where energy particles move away from hotter to cooler regions.

• Air heated becomes less dense and rises

• Cooler condense air falls

• Cycle repeats

Efficiency

The ratio of useful output energy transfer to total energy input.

Efficiency Formula for transfer

Useful energy output transfer / total energy input transfer

Efficiency Formula

Useful power output / total power input

Renewable Energy Source

An energy source which can be replenished as quickly as it is being used up.

Non-Renewable Energy Source

An energy source collected from resources that cannot be replaced when they are used up (finite).

Renewable Examples

Solar,Wind,Biofuel,Geothermal,Hydroelectricity

Non-Renewable Examples

Fossil Fuels (coal,natural gas,crude oil) and nuclear

Thermal Conductivity

How well a material conduct heat.

Work Done

The energy transferred when a force acts over a distance

Work done formula

force x distance

Pro/Cons Renewable

Its infinite,Environmentally friendly/High Upfront costs not always reliable

Pro/Cons Non Renewable

Used in any conditions(weather), quite cheap, can meet demands / Finite resource,Harmful and produces toxic gases.

Wind Energy

The energy captured by transforming the motion of air into electrical energy using a turbine

Solar Energy

energy that comes from the sun

Geothermal Energy

Energy from steam or hot water produced from hot or molten underground rocks.

Biofuel Energy

Energy that comes from materials that were recently living, like plants or some types of garbage.

Hydroelectrical Energy

electrical power produced by flowing water that turns a turbine generator

Fossils Fuels

Energy that comes from coal,oil and natural gas.

Nuclear Energy

Energy released through nuclear fission in a nuclear reactor

Geothermal Energy Process

1 water is pumped down an injection well

2 stored heat from the Earth's interior turns the water into steam

3 steam rises from the production well

4 kinetic energy of the steam turns a turbine

5 turbine turns a generator

6 generator generates electricity

Wind Energy Process

1. Turbine blades rotate in the wind

2. The turbines is then linked to generator and turns it to produce electricity.

Solar Energy Process

1. Radiation from the sun hit the solar cell

2. The radiation is then converted into an electrical current

3. This current is then givens straight to electrical components like batteries

Nuclear Energy Process

1.Nuclear fission from nuclear fuels to create the energy need to heat water.

2. The energy then heats the water into steam which turns a turbine which turns a generator to generate electricity

3.Cooler water returns to the boiler

Fossil Fuels Energy Process

1. Fossil fuels are used to light a fire in a boiler

2. The fire than heats the water into steam which turns a turbine which turns a generator to generate electricity

3.Cooler water returns to the boiler

Hydro electrical Energy Process

1. Water is blocked by a dam and made to go thorugh a different route

2.The water then passes through the turbine which then turn the generator to generate electricity.

Bio fuel Energy Process

1. Biofuel is used to light a fire in a boiler

2. The fire than heats the water into steam which turns a turbine which turns a generator to generate electricity

3.Cooler water returns to the boiler

Wave

An oscillation that transfers energy with transferring any matter by making particles of the substance oscillate.

Transverse Wave

Waves with oscillations that are perpendicular to the direction

of travel/energy transfer. (EM Waves)

Longitudinal Waves

Waves with oscillations that are parallel to the direction of

travel/energy transfer.(Sound Waves)

Crests

high points on a wave

Throughs

low points on a wave

Rest Position

The position where the wave is at rest, half way between the crest and trough.

wavelength

The distance from a point on one wave to the same point on the adjacent wave (ie. peak to peak or trough to trough or wave to wave).

amplitude

The maximum displacement of a wave from its undisturbed (rest) position.

frequency

The number of waves passing a given point in a second.

Period of a wave

The amount of time taken for a full cycle of a wave to be comepleted.

Time , Period Formula

P=1/frequency(hz) or 1/T (s)

Compression

Particles are bunched up together

Rarefraction

Particles are spread out

Wave Speed

v=fλ velocity(m/s)=wavelength(m)*frequency(hz)

Waves at a boundary (between two different materials) can

- Absorption (by material)

- Reflection

- Transmission (travel through material while undergoing refraction)

How to draw ray diagram for reflection

1. Draw normal perpendicular to the boundary at the point of incidence.

2.Measure angle of incidence and repeat on the other side

3.Then draw reflected ray on other side

Angle of incidence

Angle between incoming wave and normal

Angle of reflection

Angle between reflected wave and normal

Law of reflection

angle of incidence = angle of reflection

Specular Reflection (Smooth boundary)

when waves are reflected in a single direction by a smooth surface (gives clear reflection)

Diffuse Reflection (Bumpy Boundary)

When waves are reflected by rough surfaces and so are scattered in different directions as the normals for each bump are different.

How to draw a ray diagram

1. Draw the boundary between the materials and the normal at the point of incidence (perpendicular to boundary)

2. Draw incident ray that meets the normal at the point

3. Draw refracted ray, if the second material is denser than the first then the refracted ray will bend towards the normal

4. If the material is less dense that the ray will bend away from the normal.

Refraction through medians

Waves slows down at at a denser median and speed up at a less dense median. Frequency stays the same however wavelength increases and decreases.

EM Spectrum Order

radio, micro, infrared, visible, UV, x-ray, gamma (increasing frequency and decreasing wavelength from left to right)

EM Spectrum

A continuous spectrum of all the possible wavelengths of electromagnetic waves.

EM Waves Speed

Travel at same speed in a vaccum (3*10^8) and same speed in air.

Diffract

Diffraction is the spreading out of waves as they pass through an aperture or around objects

Dispersion

Dispersion is defined as the spreading of white light into its full spectrum of wavelengths.

Radiowave

Used for television and radio signals. They can be produced by

oscillations in electrical circuits.(alternating current)

Microwaves

Used for satellite communications and for cooking food.

Infared Radiation

Used for cooking food, electrical heaters and infrared imaging.

Visible Light

Electromagnetic radiation that can be seen with the unaided eye

Ultra Violet Light

invisible light of shorter wave lengths and beyond violet in the spectrum

X ray

a form of energy that travels in waves

Gamma Rays

high-energy electromagnetic waves emitted from a nucleus as it changes from an excited state to a ground energy state

Visible Light Colour

ROYGBIV

Ionising Radiation

Type of radiation such as UV, X ray or gamma rays that can cause mutations in DNA and damage to cells.

Convex Lens

A lense that curves inwards and refracts everything away. (Virtual Images)

concave lens

A lense that curves outwards and refract parallel line into a focal point (real image sometimes virtual if too small to meet)

How to draw ray diagrams concave

1. Lens with arrows facing outwards

2. Draw line going from the top of object through middle and touching top of lense.

3. Draw a virtual line from the top of the lense meeting point to the focal point and continue that line on the other side with a solid line.

4. Point where they meet is where image is reflect.

How to draw ray diagrams convex

1. Lens with arrows facing inwards.

2. Draw line going from the top of object through middle and touching top of lense.

3. Draw a real line through the focal on the other side draw until two lines meet.

4. Point where they meet is where image is reflect.

(Sometimes when it is too small to meet go backwards and draw a virtual image)

How to describe image

- Virtual or Real

- Inverted or Upright

- Smaller or Larger

System

A group of objects that interact with each other. Anything outside it is called the environment.

Fluid

A fluid is a substance in which the particles are free to move around. They include both liquids and gases.

Conduction Process

1.As one end of a solid object is heated, energy is transferred to the kinetic energy stores of the particles in that end.

2.This causes the particles to vibrate faster, and so they collide with their neighbouring particles more often.

3.As the collisions transfer kinetic energy, their neighbours also vibrate faster and collide more often with their neighbours.

4.This process repeats over and over again so that energy is effectively passed along the object from one particle to the next.

5.Even though it's kinetic energy that's being passed between particles, when considering the object as a whole we say that it's heat (or thermal energy) that's being transferred.

Convection Process

1.As a fluid is heated the particles gain kinetic energy and spread further apart.

2.This causes the fluid to become less dense and so it will rise above any cooler fluid that hasn't been heated (because that fluid is more dense).

3.As the fluid cools down it will become more dense again, and so sink back down.

4.If this process takes place in a limited space, like a container or a room, it can create a convection current.

Friction

The resistance that an object encounters when moving across a solid, or moving through a liquid

Investigating Refraction Practical

1. Trace the transparent rectangular block on a piece of paper. Then shin a ray box at it.

2. The the incident ray and the emerging ray and remove the block

3. Join up the two rays and add the normal at the incident ray and measure the angle of incidence and refraction.

4. Try with different materials of block keeping angle of incidence same throughout.

Investigating Reflection

1. Draw a straight line across a piece of paper

2. Place a straight edged object on the paper so that it lines up with the line

3. Shine a ray of light at the objects surface and trace the incoming and reflected light beams. Add a normal at Point of incidence.

4. Record angles, and the width and brightness of reflected ray

5. Repeat this experiment with different objects. Mirrors should be clear and smooth and paper should cause the beam to be wider and reflect or not shown at all.

Fluorescence

Ultraviolet light energy being absorbed and re-emitted as visible light

Black Body

a theoretical object which is both a perfect absorber and emitter of radiation

Intensity

AS the temperature of an object increase the intensity of every emitted wavelength increases.