Formula Centre

Formula guides and key subject rules for every grade and subject, with worked examples and practice.

Grade 4 Natural Sciences essentials

Natural Sciences • Essential reference • Grade 4

Input energy = Useful output energy + Wasted energy
Input energyEnergy supplied to a system (J)

When to use it

Use when tracing energy transfers in systems.

Worked example

100 J input = 70 J useful + 30 J wasted.

Common mistakes

  • Saying energy disappears instead of being transferred.

Practice question

Find wasted energy when input is 80 J and useful output is 55 J.

Grade 5 Natural Sciences essentials

Natural Sciences • Essential reference • Grade 5

Input energy = Useful output energy + Wasted energy
Input energyEnergy supplied to a system (J)

When to use it

Use when tracing energy transfers in systems.

Worked example

100 J input = 70 J useful + 30 J wasted.

Common mistakes

  • Saying energy disappears instead of being transferred.

Practice question

Find wasted energy when input is 80 J and useful output is 55 J.

Grade 6 Natural Sciences essentials

Natural Sciences • Essential reference • Grade 6

Input energy = Useful output energy + Wasted energy
Input energyEnergy supplied to a system (J)

When to use it

Use when tracing energy transfers in systems.

Worked example

100 J input = 70 J useful + 30 J wasted.

Common mistakes

  • Saying energy disappears instead of being transferred.

Practice question

Find wasted energy when input is 80 J and useful output is 55 J.

Grade 7 Natural Sciences essentials

Natural Sciences • Essential reference • Grade 7

Input energy = Useful output energy + Wasted energy
Input energyEnergy supplied to a system (J)

When to use it

Use when tracing energy transfers in systems.

Worked example

100 J input = 70 J useful + 30 J wasted.

Common mistakes

  • Saying energy disappears instead of being transferred.

Practice question

Find wasted energy when input is 80 J and useful output is 55 J.

Grade 8 Natural Sciences essentials

Natural Sciences • Essential reference • Grade 8

Input energy = Useful output energy + Wasted energy
Input energyEnergy supplied to a system (J)

When to use it

Use when tracing energy transfers in systems.

Worked example

100 J input = 70 J useful + 30 J wasted.

Common mistakes

  • Saying energy disappears instead of being transferred.

Practice question

Find wasted energy when input is 80 J and useful output is 55 J.

Grade 9 Natural Sciences essentials

Natural Sciences • Essential reference • Grade 9

Input energy = Useful output energy + Wasted energy
Input energyEnergy supplied to a system (J)

When to use it

Use when tracing energy transfers in systems.

Worked example

100 J input = 70 J useful + 30 J wasted.

Common mistakes

  • Saying energy disappears instead of being transferred.

Practice question

Find wasted energy when input is 80 J and useful output is 55 J.