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PHYSICS · Stage 7 · Chapter 1: Energy

Physics 1.2 Asking questions about energy — Scientific Enquiries

5 min read 7 parts Lesson 2 of 8

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Lesson summary

1.2 Asking questions about energy — Scientific Enquiries — Alhussan International Academy — Physics (Stages 7–9) notes: Recognise different ways of answering scientific questions, decide whether a question can be answered by a practical investigation, and plan a fair test.Differe…

  • Different questions
  • Science and questions
  • Practical investigations
  • Observation over time
  • Pattern seeking
  • Classifying

Part 1 of 7Types of question

  • Different questionsquestions about energy include which fuel heats water fastest, how much fuel Africa will need in the future, which city uses the most coal, whether fossil fuels should be used to cook food, and which fuel is best.
  • Science and questionsthere are many ways of finding answers, but not every question can be answered using science.
  • Practical investigationsa question such as "Which fuel heats up water the fastest?" can be answered by an investigation, whereas "Which fuel is best?" cannot, because "best" depends on opinion and many factors.

Part 2 of 7Types of scientific enquiry

  • Fair testone variable is changed and its effect measured.
  • Observation over timefor example recording temperature through a day, or finding out how something has changed.
  • Pattern seekingdata are collected from many examples.
  • Classifyingsorting things into groups.
  • Researchusing secondary sources, for example finding how much energy a country uses.
  • Modellingusing models to explain or predict.
  • Choicethe type chosen depends on the question.

Part 3 of 7Fair test investigation

  • Fair test an investigation in which you change one variable (something that can be changed) and keep all the other variables the same.
  • Why it worksif everything stays the same except the variable of interest, nothing else can affect the measurements.
  • Set upequipment is set up to take measurements to answer the question.
  • Variablesthe independent variable is what you change, the dependent variable is what you measure, and control variables are what you keep the same.

Part 4 of 7Lumusi's flow chart for a fair test

  1. Ask a question: which fuel heats up water the fastest?
  2. Make a prediction and use a scientific explanation to justify it: solid fuels store more energy, so they heat water faster than liquid or gas fuels.
  3. Test the prediction by measuring the time that candle wax, ethanol and gas take to heat 50 cm3 of water from 20 °C to 50 °C.
  4. Present the data on a chart or graph and check the evidence: are the times for the solid fuels shorter than for liquid or gas fuels?
  5. If yes, the scientific explanation is accepted, and if no, there must be a different explanation.
  • Controls — control the amount of water and the start and end temperatures of the water.
  • Repeats — scientists repeat investigations to check results and make them more reliable.

Part 5 of 7Writing a testable question

1Link two variables1 point
— a good question links two variables that can be measured.
  • "How does the height of a ramp affect the speed of a toy car?" is testable because height can be changed and speed measured.
2Energy examples
— how does the mass of a falling ball affect the depth of the dent it makes, and does the type of fuel affect how much a block of water warms up?
3Prediction1 point
— it says what you expect and why, using science ideas.
  • The higher a ball is dropped from, the higher it bounces, because it has more gravitational potential energy to transfer to kinetic energy.

Part 6 of 7Planning, presenting and evaluating

  • Plan — list the apparatus, the range and number of values (for example five heights), the number of repeats (three) and the safety precautions.
  • Results table — columns for the independent variable, each repeat and the mean, with units in the headings.
  • Graph — plot the independent variable on the x-axis and the dependent variable on the y-axis, and draw a line of best fit.
    • Use a bar chart when the independent variable is categorical, such as the type of surface.
  • Evaluate — identify anomalies, discuss sources of error such as reading a height by eye, and suggest improvements such as slow-motion video.
  • Conclusion — say whether the results support the prediction and link back to the science.

Part 7 of 7Secondary sources

  • Usenot every question can be answered by experiment, so scientists use reliable sources such as government statistics.
  • Checkingcheck who produced the data, when, and whether several sources agree.
  • Reportingstate which data are first-hand and which are secondary.

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