Do now!1 Energy Types Word

Scramble

2 Title – Energy Flow diagrams and the date

Some examples of forms of energyKinetic energy (KE)Energy due to a body’s motion.

Potential energy (PE)Energy due to a body’s position

Thermal energy Energy due to a body’s temperature.

Chemical energyEnergy associated with chemical reactions.

Nuclear energyEnergy associated with nuclear reactions.

Electrical energyEnergy associated with electric charges.

Elastic energyEnergy stored in an object when it is stretched or compressed.

All of the above forms of energy (and others) can ultimately be considered to be variations of kinetic or potential energy.

Learning Today

• Energy flow diagrams

• Energy flow circus

• Sankey diagrams

• Potential Energy – P.E.

• Homework Potential Energy Sheet

Other energy measurement examples

4200 joules (4.2 kJ) 1 food Calorie

1 000 000 J (1 MJ) Energy of a Mars bar

0.000 02 J Energy need to produce a syllable of a word

15 000 000 000 000

000 000 000 J

Energy received by the Earth from the Sun in one day

Conservation of energyEnergy cannot be created or destroyed. It can only be transformed from one form to another form.

Conservation of energy also means that the total energy in the universe stays constant.

Energy Flow diagrams – Copy please

Energy flow diagrams show energy transformations.

Work done = energy transformed For example, when a car brakes, its kinetic energy is

transformed into heat energy in the brakes.

Kinetic heat

19/04/23

Energy changesEnergy changes

To describe an energy change for a light bulb we need to do 3 steps:

Electricity Light + heat

1) Write down the starting energy:

3) Write down what energy types are given out:

2) Draw an arrow

Draw energy flow diagrams for the following…?

1) An electric fire

2) A rock about to drop

3) An arrow about to be fired

Television

electrical

light

sound

heat

What are the main energy transfers for a television (don’t forget the wasted energy)?

Car engine

chemical

kinetic

sound

heat

What are the main energy transfers for a car engine (don’t forget the wasted energy)?

Radio

electrical

sound

heat

What are the main energy transfers for a radio (don’t forget the wasted energy)?

Pendulum oscillation

GRAVITATIOINAL POTENTIAL ENERGY

KINETIC ENERGYMAXIMU

M

MINIMUM

MAXIMUM

ZERO

The total energy, gravitational potential plus kinetic, remains the same if there are no significant resistive forces

Wasted sound energy

Can you name some devices that waste energy as sound?

_____________

_____________

_____________

_____________

_____________

_____________

_____________

_____________

Hairdryer

Washing machine

Car engine

Computer

Microwave

Bunsen burner

Wind turbine

Dish washer

Wasted heat energy

Can you name some devices that waste energy as heat?

_____________

_____________

_____________

_____________

_____________

_____________

_____________

_____________

Computer

Turbine

Motor

Transformer

Any electrical device

Television

Radio

Car engine

What happens to wasted energy?

Wasted e_____ spreads out (d_______) into the s_________.

This makes the energy harder to r____.

Remember energy can not be c______ or d_______.

What happens to the wasted energy you get whenever energy is changed from one form to another?

This is why it is important to r_____ the amount of wasted energy there is.

19/04/23

Energy Transfer diagramsEnergy Transfer diagrams

Consider a light bulb. Let’s say that the bulb runs on 100 watts (100 joules per second) and transfers 20 joules per second into light and the rest into heat. Draw this as a diagram:

100 J/s electrical energy

“Input” energy “Output” energy

80 J/s heat energy (given to

the surroundings)

20 J/s light energy

19/04/23

Example questionsExample questionsConsider a kettle:

1) Work out each energy value.

Sound energy

Wasted heat

Heat to water

2000 J/s electrical energy

Consider a computer:

150 J/s electrical energy

10 J/s wasted sound

20 J/s wasted heat

Useful light and sound

1) How much energy is converted into useful energy?

Here is a more complex energy transformation Here is a more complex energy transformation diagram, the sort used by engineers.  diagram, the sort used by engineers.  This one is for an aeroplane engine.This one is for an aeroplane engine.

19/04/23

Choose appropriate words to fill in the gaps below:

Energy is required to do ________.

Energy is measured in ________ (J)

Energy cannot be created or ___________ but can only change ________.

Kinetic energy is the energy possessed by __________ bodies.

When an object is lifted up it gains gravitational _____________ energy.

Heat or __________ energy is often produced as a _________ energy form, dissipated to the surroundings.

workformmoving joulespotential thermal destroyed

WORD SELECTION:

wasted

work

form

moving

joules

potential

thermal

destroyed

wasted

19/04/23Gravitational Potential Gravitational Potential EnergyEnergy

Gravitational potential energy is the energy an object has because of its position in a gravitational field

GPE = Weight x Change in height

(Joules) (newtons) (metres)

GPE

HW

19/04/23Gravitational Potential Gravitational Potential EnergyEnergy

Gravitational potential energy is the energy an object has because of its position in a gravitational field

GPE = Weight x Change in height

(Joules) (newtons) (metres)

GPE

HW

19/04/23Some example questions…Some example questions…How much gravitational potential energy have the following

objects gained?:

1. A brick that weighs 10N lifted to the top of a house (10m),

2. A 10,000N car lifted by a ramp up to a height of 50cm,

3. A 70kg person lifted up 50m by a ski lift.

How much GPE have the following objects lost?:

1. A 2N football dropping out of the air after being kicked up 30m,

2. A 0.5N egg falling 10m out of a bird nest,

3. A 10,000N car falling off its 50cm ramp.

4. Mr Richards when bungi-jumping off a 110-metre high bridge in Zambia in August

Don’t forget! Test!

• Use the revision sheet to help you study!

• Test on Thursday 26th January

Energy Circus

Around the room are a few examples of energy changes (some simple, some a little more complicated!)

For each example I want you to write the name of the experiment and then the energy flow diagram for that experimentYou will have 2 minutes on each example.

Ready?

Go!

Sankey Diagram

A Sankey diagram helps to show how much light and heat energy is produced

Sankey Diagram

The thickness of each arrow is drawn to scale to show the amount of energy

Sankey Diagram

Notice that the total amount of energy before is equal to the total amount of energy after (conservation of energy)

Efficiency

Although the total energy out is the same, not all of it is useful.

Efficiency

Efficiency is defined as

Efficiency (%) = useful energy output x 100

total energy input

Efficiency

Efficiency is defined as

Efficiency (%) = useful energy output x 100

total energy input

Can you copy this (with title) please?

Example

Efficiency = 75 x 100 = 15%

500

Energy efficient light bulb

Efficiency = 75 x 100 = 75%

100

Energy efficient light bulb

Efficiency = 75 x 100 = 75%

100 That’s much better!

More complex examples

Let’s try some questions!

Stick the sheet into your books and answer the questions