What does the law of conservation of energy say?

Energy cannot be created or destroyed, only transferred between stores.

Name the four energy transfer pathways.

Mechanical, electrical, heating and radiation.

What is the heating pathway?

Thermal energy moving from a hotter to a colder place because of a temperature difference.

What is meant by wasted energy?

Energy transferred to stores that are not useful, usually the thermal store of the surroundings.

What does 'dissipate' mean?

To spread out into the surroundings so that the energy is no longer useful.

What does the width of an arrow in a Sankey diagram show?

The amount of energy (in joules) being transferred.

Which stores are found between electric charges and between magnets?

Electrostatic and magnetic stores.

Energy stores and transfersIB MYP Sciences: Flashcards

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Name the unit of energy.

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Name the unit of energy.: The joule (J).
What does the law of conservation of energy say?: Energy cannot be created or destroyed, only transferred between stores.
In which store is the energy of a moving bus?: The kinetic store.
In which store is the energy of a stretched spring?: The elastic potential store.
In which store is the energy of food and fuel?: The chemical store.
Name the four energy transfer pathways.: Mechanical, electrical, heating and radiation.
What is the heating pathway?: Thermal energy moving from a hotter to a colder place because of a temperature difference.
What is meant by wasted energy?: Energy transferred to stores that are not useful, usually the thermal store of the surroundings.
What does 'dissipate' mean?: To spread out into the surroundings so that the energy is no longer useful.
What does the width of an arrow in a Sankey diagram show?: The amount of energy (in joules) being transferred.
A motor takes in 400 J and transfers 300 J usefully. How much energy is wasted?: 100 J (400 - 300).
Which stores are found between electric charges and between magnets?: Electrostatic and magnetic stores.

Exam questions on Energy stores and transfers

A child in Nairobi winds up a clockwork toy car, puts it on the floor and lets it go. The toy speeds across the floor, then gradually slows down and stops.
Describe the energy transfers that happen from the moment the spring is released until the car stops.2 marks
A hydroelectric power station in Norway has a reservoir high up a mountain. Water runs down large pipes to turbines at the bottom, and the turbines turn a generator that supplies electricity to nearby towns.
Describe the energy transfers from the water at the top of the pipes to the electricity leaving the generator.2 marks
A class in Melbourne compares three bouncing balls, X, Y and Z. Each ball is dropped from a height of 1.00 m onto the same hard floor and the height it rebounds to is measured. The students predict that a ball that rebounds lower transfers more energy to the surroundings. The mean rebound heights were 0.80 m for ball X, 0.55 m for ball Y and 0.30 m for ball Z.
Identify the independent variable, the dependent variable and one control variable in this investigation.3 marks

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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).