1.8Chapter 1: Energy

Chapter 1 Review: Energy — Alhussan Physics - Stage 7 Revision Notes & Topical Questions

5 min read 7 parts Lesson 8 of 8 1 quiz

📚 Alhussan Physics - Stage 7 Hub / Topical Revision

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Lesson summary

1.8 Chapter 1 Review: Energy — Alhussan International Academy — Physics (Stages 7–9) notes: Revise energy stores, transfers, gravitational potential and kinetic energy, elastic energy and investigation skills.Stores — energy is measured in joules and held in chemical, kinetic, gr…

Conservation
Dissipation
Efficiency
Trampoline
Stretched objects
Independent variable

Part 1 of 5Stores, pathways and conservation

1Stores

Stores energy is measured in joules and held in chemical, kinetic, gravitational potential, elastic potential, thermal and nuclear stores.

2Pathways

Pathways energy moves by mechanical, electrical and heating pathways, and by waves such as light and sound.

3Conservation

Conservation energy is never created or destroyed.

4Dissipation

Dissipation in every transfer some energy is dissipated as thermal energy, so the useful output is less than the input.

5Efficiency

Efficiency useful output ÷ total input × 100%.

Part 2 of 5Gravitational potential and kinetic energy

GPE

GPE the higher an object is above the ground and the greater its mass, the more GPE it has: GPE = m × g × h.
What the symbols mean: E_p = gravitational potential energy gained (J) · m = mass (kg) · g = 9.81 N kg⁻¹ · h = change in height (m)
To order objects by GPE, compare mass and height, so Josie on the top diving board has more GPE than a child on a low board.

Falling

GPE decreases and KE increases.
Just before hitting the mat, KE is at a maximum.
At the top of a jump, KE is zero and GPE is greatest.

Trampoline

Trampoline at the top of a bounce energy is mostly gravitational potential,
- and at the lowest point the trampoline is stretched and has elastic potential energy.
As a person leaves the mat all the energy is kinetic.

Part 3 of 5Elastic energy and bouncing

Stretched objects

Stretched objects a stretched spring has elastic potential energy.

Bouncing

Bouncing a ball never bounces to its original height because some energy is dissipated by sound and heating.

Part 4 of 5Pendulum and investigation skills

Investigation

Chinonye times 10 swings for different children on a swing and calculates the periods, finding that a longer swing has a longer period.

Independent variable

Independent variable the length of the swing.

Dependent variable

Dependent variable the time for 10 swings.

Controls

Controls the angle and number of swings.

Method

Method repeat the timings, find the mean and use a table with headings and units.

Improvement

Improvement use video to time the swings.

Skill	Reminder
Calculating period	Total time ÷ number of swings
Efficiency	Useful ÷ total × 100%
GPE	m × g × h

Part 5 of 5Checking answers

Stores

Stores check which store increases and which decreases.

Falling ball

GPE decreases and KE increases, but at the top of a bounce KE is zero.

Units

Units energy in J, force in N, height in m.

Efficiency

Efficiency it has no units but can be written as a percentage.

Graphs

Graphs read them carefully and note whether a line is straight or curved.

Key terms

Term	Meaning
Efficiency	the useful energy output divided by the total input.
Dissipation	energy spreading out into the surroundings.
Elastic potential energy	the energy stored in a stretched or squashed object.
Period	the time for one oscillation.
Gravitational potential energy	the energy stored because of height.

Avoid these mistakes

Using cm instead of m for height — convert to metres before using GPE = m × g × h.

Forgetting that energy is dissipated — some always ends up in the surroundings.

Saying energy is used up — energy is transferred, not destroyed.

Confusing period with frequency — the period is the time for one swing.

Last updated: 14 October 2026