Atmosphere, resources and life-cycle decisions
導入済み| English | 意味 |
|---|---|
| life-cycle assessment/laɪf ˈsaɪkl əˈsesmənt/ | ライフサイクル評価 |
| functional unit/ˈfʌŋkʃənl ˈjuːnɪt/ | 機能単位 |
What would explain this observation?
- A reusable container can require more energy to manufacture than a single-use one. Its impact depends on how often it is used and what happens at disposal.
- Start with a prediction. State the quantities or features you would compare, then decide what evidence could distinguish two explanations.
Build the model
- A life-cycle assessment 生命周期评价 considers raw materials, manufacture, transport, use and end-of-life processes. Greenhouse gases absorb and emit infrared radiation; pollution and climate effects are related but distinct questions.
- life-cycle assessment: Assessment across production, use and disposal; functional unit 功能单位: The common service used for a fair comparison.
Which comparison uses a consistent functional unit?
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
A fair life-cycle comparison keeps the functional unit constant - the same service, such as one litre delivered one thousand times. Comparing one bottle against an arbitrary number of bags or matching colours measures nothing useful.
Match each technical term to its precise meaning.
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
Use the definitions to distinguish related quantities and processes.
Choose evidence that can test it
- Define the functional unit before comparing products. The same delivered service, such as carrying one litre of water a hundred times, is fairer than comparing one object with another regardless of lifetime.
- List system boundaries, energy sources and assumptions. Compare water demand, emissions and waste separately before making a judgement. Explain whose priorities affect the decision and where the data are uncertain.
Which two habits make the investigation or model in this case more defensible?
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
Stating the conditions and assumptions lets others repeat the work exactly, and recording the supporting evidence lets them check the conclusion. Hiding disagreeing results removes the evidence that could challenge a wrong conclusion, and one measurement can never establish a wider claim.
Work from known quantities
- State the known values and their units. Choose the relation because its assumptions fit this case, then rearrange before substitution.
- Known: a reusable item requires 1,000 energy units to make and 10 per use; a disposable item requires 60 per use. Equality occurs when 1,000 + 10n = 60n. Rearranging gives 1,000 = 50n, so n = 20 uses under this simplified model.
A reusable item costs 600 energy units initially and 5 per use; disposables cost 35 per use. Find break-even uses. Use the same sequence: known quantities → model → relation → substitution → unit and interpretation.
A reusable item costs 600 energy units initially and 5 per use; disposables cost 35 per use. Find break-even uses.
難易度 2/5 · 140 コイン + 今日初回完了時に小ボーナス付与
The result is 20 uses. Known: reusable item 600 units initially plus 5 per use; disposable 35 per use. Break-even: 600 + 5n = 35n. Rearranging: 600 = 30n, so n = 20 uses. Above 20 uses the reusable item is ahead under this simplified model.
Check the conclusion and its limits
- A break-even model is sensitive to cleaning, transport and disposal assumptions. Recyclable does not guarantee that an item is actually collected and recycled.
- Return to the original observation. Explain what the result supports, which conditions it assumes, and one way to test a competing explanation.
A recyclable product is always recycled after use. This claim is false: Recyclable means the material CAN be recycled with the right collection and processing; actual recycling depends on local systems and behaviour. Many recyclable items are never collected.
Atmosphere, resources and life-cycle decisions: Define the functional unit before comparing products. The same delivered service, such as carrying one litre of water a hundred times, is fairer than comparing one object with another regardless of lifetime.
A recyclable product is always recycled after use.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
Recyclable means the material CAN be recycled with the right collection and processing; actual recycling depends on local systems and behaviour. Many recyclable items are never collected.
Assessment across production, use and disposal: write the technical term.
難易度 1/5 · 100 コイン + 今日初回完了時に小ボーナス付与
life-cycle assessment means Assessment across production, use and disposal.