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Energy Transfers

• Everything we do involves a transfer of energy.

There are seven stores of energy:

1. THERMAL– all objects have energy in their thermal energy store. The hotter an object is, the higher its temperature and consequently a higher thermal energy store.

2. MAGNETIC– magnets that attract or repel store each other have energy in their magnetic energy store. (Remember: magnets which attract come together whereas repelling magnets do not touch each other unless forced).

3. CHEMICAL– this is energy that can be released by chemical reactions occurring. Examples: food, batteries and fuels.

4. ELECTROSTATICtwo electric charges which attract or repel each other have energy in their electrostatic energy stores. (like magnetic energy stores but with charges instead).

5. GRAVITATIONAL POTENTIAL– anything that can fall (is high up) is in a gravitational field. It has energy in its gravitational potential energy store. The higher it is, the more stored energy it has.

6. KINETIC– kinetic means moving. Anything which moves has energy in its kinetic energy store.

7. ELASTIC POTENTIAL– anything that can be stretched (elastic bands, springs) has energy in its elastic energy store.

• Between energy stores, energy can be transferred.
• When something happens to an object the store of energy in the object you are transferring to increases and decreases in the object you are transferring energy from.

Examples:

1. Dropping a ball. It moves through a gravitational field so energy transfers FROM its gravitational energy store TO its kinetic energy store.

2. Burning a fuel. Energy transferred FROM its chemical energy store TO thermal energy of surroundings.

3. Switching on a basic electric circuit (battery, motor, switch). Energy transferred FROM chemical energy store in battery TO kinetic energy store in the motor. As the motor turns the parts rub together which generates heat. So, energy transfer FROM kinetic energy TO thermal energy store.

4. Stretched spring. When the spring is released, the stored elastic energy transfers TO kinetic energy store.

5. Food. Has energy stored in chemical energy stores. As food goes through your body, it is changed during chemical processes in the body (metabolised). This transfers energy to the body for useful things such as walking and maintaining body temperature.

4 main ways of transferring energy:

1. Mechanically– applying a force to make an object move.

2. Heating – energy transferred from hotter object to cooler objects.

3. Electricallyelectric charges moving around a circuit due to a potential difference.

4. Light and sound– light and sound waves carrying energy from one place to another.

• When a force moves an object, energy is transferred. If a force moves an object a distance, energy is transferred. The force need a supply of energy. Then, energy transferred by moving the object (kinetic energy stores).
• To work out how much energy has been transferred:

Energy transferred (in Joules, J) = Force (in Newtons, N) X Distance (in Metres, m)

How long have you…? (present perfect 4) Exercises

Use the information given to create questions beginning with ‘How long…?’

• It is snowing.

• The weather is shining.

• John and Kate are married.

• My brother has gone on holiday.

• My aunty and uncle live in Canada.

• My sister is a teacher.

• I work at the chemist.

• I’ve known Susan since I was a baby.

• Jonathan is learning to speak to Mandarin.

Fill in the missing gaps in the sentences using the present perfect (=has/have + past participle)

• I have known Kate a long time.

• My brother has been playing the piano he was 11 years old.

• My mum and dad on holiday to America. They

gone since last Sunday.

• I Ben and Emma since primary school.

We to the same primary and secondary school.

• My sister learning to speak French because she
is going to France next month.

Use the appropriate words in the missing gaps.

have you lived       lives      to

has been       works        have known

I have bought       have worked.

• My sister in Spain. She is studying Spanish

with her friend Rosie. I Rosie since I was 5.

• Spencer like with Jamie. They have worked

together for 2 years.

• How long in Australia?

• a new dress for prom.

• He to Thorpe park.

Challenge: Create 4 of your own questions beginning with ‘How long……?’

1.

2.

3.

4.

1 2 3 4 5 6

“Every accomplishment starts
With the decision to try.” Gail Dever

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