Work and Energy
MYP Year 5 Sciences: Physics — Work and Energy
Every question in this unit is really the same question wearing different clothes: where did the energy go, and how fast did it get there? A rod conducting heat, a piston squeezing gas, a Sankey diagram for a light bulb, a ball falling off a cliff, a motor lifting a crate, a power station burning coal — all of them are asking you to track joules from one place/form to another without ever letting them appear from nowhere or vanish into nothing.
Overview — The Shape of This Chapter
Work and Energy stitches together six ideas you've met piece by piece: how heat moves (conduction, convection, radiation), how force spreads over area (pressure), how real machines split energy into useful and wasted output, how energy changes form while its total stays fixed, how work/power/efficiency are calculated, and finally where the energy actually comes from (renewable vs non-renewable resources).
- One law underpins everything here: energy is never created or destroyed, only transformed or transferred — 'wasted' energy still exists, it's just spread out as heat that's hard to reuse.
- Heat and temperature are NOT the same physical quantity — mixing them up is the single most common conceptual error in this unit's written answers.
- Real machines are never 100% efficient. If a calculated efficiency comes out above 100%, that's a red flag that input/output values got swapped.
- Resource questions blend physics (how the fuel behaves) with sustainability (whether it runs out) — command terms like Discuss and Evaluate expect both sides.
The shape of the chapter
Command terms that decide your mark
| Command term | What it demands | AO | Mark-earning move |
|---|---|---|---|
| Identify | State the specific name/value/pattern requested | AO1 | Answer must name the exact thing (e.g. 'material' not 'copper is fastest') — vague answers lose the mark. |
| Describe | Give a detailed factual account of what happens | AO1/AO2 | State the sequence/pattern — no reasoning or mechanism required yet. |
| Explain | Give reasons — the mechanism or cause behind an observation | AO2 | Must include the 'because'; a bare description with no causal link scores zero on an Explain command. |
| Calculate | Produce a numerical answer with working shown | AO3 | Method marks live in the working — a correct final number with no steps can still lose marks. |
| Compare | State similarities AND differences between two things | AO2/AO3 | One-sided answers (only differences, or only similarities) are capped at partial credit. |
| Discuss | Present points for and against, balanced | AO3 | Both sides must be weighed — a one-sided 'discussion' is marked as incomplete. |
| Evaluate | Weigh strengths and weaknesses and reach a judgement | AO3 | Must end in a stated conclusion — a list of pros/cons with no verdict misses the top mark band. |
Key point
Overview