Identify starting and finishing energy forms in familiar devices and moving systems.
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Method and worked examples
An energy transfer moves energy between objects or places; a transformation changes the form or store being described. A falling stone transforms gravitational potential into kinetic energy. A battery torch supplies energy from a chemical store through an electrical circuit, producing light and heating.
Real devices can have several outputs. A motor produces motion, heating and sound. Friction transfers some motion-related energy into thermal energy of interacting surfaces and surroundings; it does not destroy it. Identify the intended output separately from other outputs. Useful depends on purpose: heating suits a heater but is often unwanted in a drive motor.
Example 1
Name a simple energy chain for a falling stone before it hits the ground.
Gravitational potential energy decreases while kinetic energy increases, with some possible transfer to the air.
Example 2
A battery motor turns a fan and becomes warm. Identify the intended and other output.
The intended output is motion of the fan and air. Thermal energy transferred to surroundings is another output; some sound may also occur.
Watch out:It is transferred mainly into thermal energy of surfaces and surroundings, becoming more dispersed.
Following energy transformations practice | Year 8 Science | Ascent Arcade