Science and public issues
Introduced| English | Meaning |
|---|---|
| risk/rɪsk/ | The possibility of an adverse outcome, often assessed using its likelihood and consequences. |
| communicating uncertainty/kəˈmjuːnɪkeɪtɪŋ ʌnˈsɜːtənti/ | communicating uncertainty |
Lower power answers only one question
- A school compares a 60 W lamp with a 10 W lamp for 5 hours daily over 20 days. Assume both draw their stated constant power during the same 100-hour operating period.
- This permits an energy estimate. It does not yet establish equal brightness, suitability, total cost or a decision to replace the lamps.
In this fictional lamp exercise, which statement is a recommendation rather than a numerical estimate?
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The recommendation goes beyond a numerical estimate. Suitability, cost, values and approval must also be considered.
Calculate energy in compatible units
- Electrical energy follows $E=Pt$. Convert power to kilowatts when time is in hours: 60 W is 0.060 kW and 10 W is 0.010 kW.
- The estimates are $E_{\text{old}}=0.060\times100=6.0\ \text{kWh}$ and $E_{\text{new}}=0.010\times100=1.0\ \text{kWh}$. Their difference is $\Delta E=6.0-1.0=5.0\ \text{kWh}$.
Under the stated constant-power, 100-hour assumptions, what energy reduction is estimated in kWh?
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E = Pt gives 6.0 and 1.0 kWh; ΔE = 5.0 kWh.
Distinguish operating savings from total cost
- If the fictional task adds a constant tariff of 0.80 RMB per kWh, the energy-cost reduction is $\Delta C=\Delta E\times r=5.0\times0.80=4.0\ \text{RMB}$ over that period.
- Without a tariff, energy alone cannot give a money saving. Even with it, purchase, installation and maintenance costs remain separate; a 4.0 RMB operating saving need not mean a lower total cost.
At the fictional constant tariff of 0.80 RMB/kWh, what energy-cost reduction follows from 5.0 kWh saved, in RMB?
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ΔC = ΔE × r = 5.0 × 0.80 = 4.0 RMB; other costs are separate.
Describe the relevant risk and comparison
- Risk 风险 involves both the likelihood and seriousness of harm under stated conditions. A rare severe harm and a frequent minor harm are different patterns, not interchangeable labels.
- Name the use conditions, possible harm and relevant alternative. A broad “safe” claim needs clarification; missing evidence does not prove no risk.
Assessing a risk properly needs which of these? Choose all that apply.
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Likelihood, seriousness and relevant alternatives help assess a decision. Clarify what safe means under the actual use conditions; a broad label is not automatically unanswerable.
Communicate what the estimate leaves unknown
- Communicating uncertainty 传达不确定性 includes stating assumptions and limits. Here, operating time and constant power are supplied assumptions; no measured uncertainty interval is provided.
- Report the 5.0 kWh estimate alongside what could change it, such as different hours of use or actual power. Do not invent a range or promise a conclusion will never change.
A faithful summary is: “Under the stated 100-hour, constant-power assumptions, estimated energy use falls from 6.0 to 1.0 kWh. At the fictional tariff, that saves 4.0 RMB in energy costs; lighting suitability and other costs need checking.”
Which summary faithfully reports the supplied lamp calculation and its limits?
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The bounded summary preserves the estimate and missing inputs. It does not promise that a conclusion remains unchanged after future evidence.
Stating uncertainty automatically makes an otherwise identical finding weaker evidence.
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Reporting uncertainty accurately helps interpret the claim. It does not by itself make every study stronger than another; compare methods, scope and actual evidence.
Use evidence to inform a decision
- A measurement can answer “How much energy is used over the same period?” Decisions also involve costs, needs and values, such as whether the intended room receives suitable lighting.
- Separate the numerical estimate from the recommendation and identify the missing evidence. Analyse the supplied record; real electrical work requires school approval and authorised personnel.
Use defined comparison → equation and units → estimate → limits → decision criteria. A lower-power label alone does not settle every criterion.
Rewrite “is this lamp the best choice?” as a specific question that can be investigated with measured evidence.
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Example: “How much energy does each lamp use over the same operating period?” Other suitability and cost questions still remain.
A 4.0 RMB saving in energy costs proves a lower total cost even though purchase and installation costs are unknown.
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False: those costs can outweigh the operating saving.