1. Natural Sciences Grade 7
Term 3: Energy and Change
Potential and kinetic energy

2. Topic 2 Potential and Kinetic Energy
Potential and kinetic energy in systems
Natural Sciences - Grade 7

3. Natural Sciences - Grade 7
Flow diagram example:
NB: When drawing an energy flow diagram you need to identify:
Where the energy comes from (the input energy).
Where the energy goes ( transfer into output energy).
The changes in potential and kinetic energy in the process.
Natural Sciences - Grade 7

4. Flow diagram example: Plastic Ruler
The potential energy changes to kinetic energy when the bent ruler is released.
The ruler bends.
The bent ruler has elastic potential energy.
Natural Sciences - Grade 7

5. Flow diagram example: Water wheel
The water at a height, has gravitational potential energy.
Gravity lets the water fall onto the fins of the water wheel. Gravitational potential Energy is changed to kinetic energy.
The falling water causes the water wheel to turn.
Natural Sciences - Grade 7

6. Flow diagram example: Wind up toy car [above]
A person has to wind up the toy car. It now has elastic potential energy.
The toy car moves.
The elastic potential energy is now changed to kinetic energy.
Natural Sciences - Grade 7

7. Flow diagram example: Electrical toy car
Cells have poten-tial energy.
Circuit is closed and an electric current starts to flow.
The electric current flows and turns the motor.
The electric motor turns the wheels and the car moves [kinetic energy]
Natural Sciences - Grade 7

8. Flow diagram of the energy system
Flow diagram of the energy system of a boy eating a banana.
Banana
[potential energy].
Boy eats the banana.
Energy is stored in the boy’s muscles.
The boy runs
[kinetic energy].
Natural Sciences - Grade 7