IB Physics HL Inquiry 1 — Exploring & Designing Practical Skills research questions & hypotheses ~14 min read

Exploring a Problem

This is the creative start of the scientific process — the stage where you get to act like a real scientist. You take your curiosity and your physics knowledge, do some background research, and turn a vague idea into a focused research question and a testable hypothesis. Get this stage right and the rest of your investigation has a solid foundation; rush it, and everything downstream wobbles.

📚 What you need to know

Developing your investigation

The best investigations often begin with a simple question about a standard experiment. Instead of “measuring g,” you might ask “to what extent does the mass of a pendulum bob affect its period?” That reframing shows insight — you’re thinking about the assumptions built into a physical model, not just following a recipe.

A crucial early decision: don’t try to investigate too much at once. A strong investigation explores the relationship between one independent variable and one dependent variable, thoroughly. Avoid questions like “how do the length and mass of a pendulum affect its period?” — pick one factor and study it properly.

The single most common mistake I see at this stage is biting off too much. A question with two or three variables in it feels ambitious, but it actually makes a clean investigation impossible — you can’t tell which factor caused what. Choose one variable, go deep, and you’ll produce far better data than someone juggling three.

Consult a variety of sources

Before you can write a good research question, you need background information. This research isn’t a formality — it’s what lets you understand the underlying physics, find established values to compare against, and choose a sensible method.

Useful sources include your class notes, your textbook, the IB data booklet, reputable databases (like NIST or the CRC Handbook for material properties), and reliable simulators such as PhET. Together these give you the scientific context — the evidence that you actually understand the physics behind your question.

Formulating a research question

A good research question (RQ) is focused, specific, and clearly states the link between your independent and dependent variables. “How does gravity affect objects?” is far too general. A focused RQ usually takes 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?” — one independent variable (length), one dependent variable (period), clearly linked.

Writing a hypothesis

A hypothesis is not a guess. It’s a clear, testable statement that predicts the outcome and justifies it with established physics. The best ones follow a three-part structure:

The "If … then … because" hypothesis IF you change the independent variable… THEN the dependent variable will… (the prediction) BECAUSE a physical principle or equation justifies it (this is the part that turns a guess into science)
The “because” is what separates a scientific hypothesis from a plain prediction — it grounds the outcome in established physics.

A statement like “if the length increases, the period will increase” is just a prediction. To make it a scientific hypothesis, you add the justification: “…because the pendulum equation T = 2π√(L/g) shows the period is proportional to the square root of the length.”

EXAMPLE

Exploring an oscillation investigation — from a broad idea to a full hypothesis.

Broad idea “I’m interested in what affects the time a pendulum takes to swing.” Consulting sources & insight The textbook gives T = 2π√(L/g). Notice the mass m doesn’t appear — so the period should be independent of mass. Research question “What is the effect of the length of a simple pendulum on its period of oscillation?” Hypothesis If the length increases, then the period increases, because T ∝ √L. A focused RQ + a justified, testable hypothesis The equation did the heavy lifting: it gave both the prediction AND the reason, and it revealed which variable to leave alone (mass).
EXAMPLE

Exploring an electrical resistance investigation.

Broad idea “I want to investigate what affects the resistance of a wire.” Consulting sources & insight Resistivity is defined by ρ = RA/L, so resistance is directly proportional to length and inversely proportional to area. Research question “What is the relationship between the length of a constantan wire and its resistance?” Hypothesis If the length increases, then resistance increases proportionally, because R = ρL/A. Constantan chosen for its stable resistivity Looking up material properties told the student to hold area and material constant — the research directly shaped the design.

💡 Top tips

⚠ Common mistakes

Quick recap: Exploring turns curiosity into a focused research question (one IV, one DV) and a testable hypothesis backed by physics. Consult a variety of sources for scientific context, write the RQ as “what is the relationship between X and Y?”, and structure the hypothesis as “If…, then…, because…” with a real justification.
Once you have a sharp research question and a justified hypothesis, the next job is turning that idea into a practical, repeatable plan — choosing variables, deciding what to measure and how, and thinking through safety. That’s the whole focus of the next stage: Designing an Investigation.

Struggling to shape a research question?

Book a free meeting and we’ll turn your rough idea into a focused RQ and a properly justified hypothesis — the foundation every top-scoring IA is built on.

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