IBPhysicsDPHLRevision NotesInquiry ProcessInquiry 1: Exploring and Designing in PhysicsExploring in Physics

Exploring in Physics (DP IB Physics): Revision Note

Katie M

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Katie M

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Exploring in Physics

  • This is the creative start of the process where you act like a true scientist

  • It involves using your curiosity and existing physics knowledge to formulate a focused research question and a testable hypothesis

  • It requires independent thinking and consulting a variety of sources to understand the scientific context behind your idea and to make a clear, scientifically justified prediction

Developing your investigation

Demonstrate independent thinking, initiative, and insight

  • The best investigations often start with a simple question about a standard experiment

  • For example, "measuring the acceleration due to gravity, g."

  • You can show insight by framing it as a comparative investigation:

    • "To what extent does the mass of a pendulum bob affect its period of oscillation?"

  • This shows you are thinking about the assumptions within physical models

  • A common mistake is trying to investigate too many variables at once

  • A strong investigation explores the relationship between one independent variable and one dependent variable in depth

    • Avoid questions like "How do the length and mass of a pendulum affect its period?"

  • It is recommended that you choose just one factor and investigate it thoroughly

Consult a variety of sources

  • Before you can formulate a high-quality question, you need background information

    • This is a crucial research step

  • Good research helps you to:

    • understand the underlying physical principle

    • find established scientific values for comparison

    • identify a suitable method for collecting data

  • You can use various resources, including:

  • This research provides the scientific context for your investigation, showing that you understand the physics behind your question

Formulate research questions and hypotheses

  • A research question (RQ) must:

    • be focused

    • be specific

    • clearly state the link between the independent variable and the dependent variable

  • An RQ like "How does gravity affect objects?" is too general

  • A focused RQ usually has the form "What is the relationship between x and y?"

    • For example, "What is the relationship between the length of a simple pendulum and its period of oscillation?"

  • A hypothesis is not a guess

    • It is a clear, testable statement that predicts the outcome and includes a scientific justification

    • The best hypotheses follow an "If..., then..., because..." structure

State and explain predictions using scientific understanding

  • The "because" part of your hypothesis is where you explain your prediction

    • This explanation must be based on established physical principles, such as Newton's laws, conservation of energy, or relevant formulae

  • A hypothesis like "If the length increases, the period will increase" is just a prediction

  • To make it a valid scientific hypothesis, you must add the justification:

    • "...because the theoretical equation for the period of a simple pendulum, T space equals space 2 straight pi square root of L over g end root, shows that the period is directly proportional to the square root of the length."

Worked Example

Exploring an oscillation investigation

Broad idea:

  • I am interested in the factors that affect the time it takes for a pendulum to swing

Consulting sources and gaining insight:

  • My textbook shows that the formula for the period of a simple pendulum is

T space equals space 2 straight pi square root of L over g end root

  • This equation suggests that the period depends on the length L and the acceleration of free fall g

  • Crucially, the mass m of the pendulum bob does not appear in this equation, suggesting the period should be independent of the mass

Formulating the research question:

  • "What is the effect of the length of a simple pendulum on its period of oscillation?"

Formulating the hypothesis:

  • If the length of the pendulum is increased...

  • then the period of oscillation will also increase...

  • because the formula T space equals space 2 straight pi square root of L over g end root shows that the period T is directly proportional to the square root of the length square root of L

Worked Example

Exploring an electrical resistance investigation

Broad idea:

  • I want to investigate the factors that affect the electrical resistance of a wire

Consulting sources and gaining insight:

  • My textbook defines resistivity rho using the formula

rho space equals space fraction numerator R A over denominator L end fraction

  • where R is resistance, L is length, and A is the cross-sectional area

  • The formula shows a direct relationship between resistance and length. It also shows an inverse relationship between resistance and cross-sectional area.

  • Resistivity rho is a property of the material itself. I can find accepted values for the resistivity of different metals, like copper and constantan, from a reliable source, such as the CRC Handbook of Chemistry and Physics

Formulating the research question:

  • "What is the relationship between the length of a constantan wire of constant cross-sectional area and its electrical resistance?"

Formulating the hypothesis:

  • If the length of the constantan wire is increased...

  • then its resistance will increase proportionally...

  • because the formula R space equals space fraction numerator rho L over denominator A end fraction states that resistance is directly proportional to length, assuming a constant cross-sectional area and temperature

Worked Example

Exploring specific heat capacity

Broad idea:

  • I want to understand why different materials heat up at different rates

Consulting sources and gaining insight:

  • The syllabus defines specific heat capacity c as the energy required to raise the temperature of a unit mass by one degree, using the equation

Q space equals space m c increment T

  • Trustworthy databases, such as NIST, provide accepted values for the specific heat capacity of different materials

    • For example, the value for copper is much lower than for aluminium

  • This implies that less energy is needed to raise the temperature of copper compared to an equal mass of aluminium

Formulating the research question:

  • "How can the method of mixtures be used to experimentally determine the specific heat capacity of an unknown metal block?"

Formulating the hypothesis:

  • If a heated metal block is placed in a known mass of cool water...

  • then the specific heat capacity of the metal can be calculated...

  • because according to the principle of conservation of energy, the thermal energy lost by the metal block will be equal to the thermal energy gained by the water, allowing c for the metal to be determined from the equation:

m subscript metal c subscript metal increment T subscript metal space equals space m subscript water c subscript water increment T subscript water

Examiner Tips and Tricks

  • Struggling for an idea is normal.

    • Good starting points include:

      • A surprising or unexplained result from a class experiment.

      • Investigating a different aspect of a standard lab, such as the effect of temperature on a spring's stiffness.

      • Applying a physical concept to a real-world product, like investigating the bounce efficiency of different types of sports balls.

  • Check feasibility first.

    • Always consider if you have the right equipment, sensors, and time to actually carry out your investigation.

    • A great idea is not useful if it's not practical in a school lab.

  • Be prepared to refine your idea.

    • Your initial research might show that your first idea is not possible or practical.

      • Don't be afraid to change your RQ based on what you learn.

      • You may need to conduct additional research to help you refine the scope of your investigation.

      • This is part of the scientific process.

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    Katie M

    Author: Katie M

    Expertise: Physics Content Creator

    Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.