IB Physics SL Extended Essay Example

This statement conflicts with the rest of the report, which repeatedly models the cylinder as solid. The research question and the theoretical derivation must describe the same object consistently; otherwise the topic becomes unclear and the physics model used later cannot be fully trusted.

What specific evidence in the investigation shows that the chosen cylinder model is actually hollow rather than solid? Answering that explicitly would strengthen the focus and make the theoretical comparison defensible.

The student clearly identifies the physical relationship the investigation is built around: mass distribution, moment of inertia, and rolling acceleration. This gives the essay a clear scientific direction and shows a relevant choice of topic that can be explored experimentally.

The student should revise the question so it matches the actual apparatus and theory exactly. If the cylinder is solid, the wording should say solid cylinder; if it is hollow, the theory and calculations must be changed to the hollow-cylinder moment of inertia and predicted acceleration.

The student gives a clear conceptual explanation of moment of inertia before using formulas. That helps the reader understand why object shape matters, rather than treating the equations as isolated facts.

This should be conservation of energy. The incorrect terminology weakens the precision of the physics writing, especially in a derivation where accurate concept names matter for communication and assessment.

The cancellation of $m{R}^2$ is mathematically valid for the ideal model, but the explanation is imprecise. The student should state that the common factor is divided out algebraically, not that it is removed because mass and radius are non-zero, which is not the reason for the simplification.

The student applies the solid-cylinder model here, which does not match the stated hollow-cylinder question. That mismatch is a subject-knowledge issue because the moment of inertia must correspond to the actual object being tested.

This reasoning is not fully accurate for the ideal rolling model derived in the report, because mass cancels from the acceleration equation. The student should distinguish between what must be controlled experimentally and what the theory predicts will not affect the result.

This hypothesis shows sound use of rotational dynamics: the student links the prediction to moment of inertia rather than simply stating an outcome. That makes the reasoning physically meaningful and testable.

The aim is clear, but it again conflicts with the repeated reference to a hollow cylinder elsewhere. The student needs one consistent object description throughout the essay so the terminology and theory align with the actual investigation.

This is not quite correct terminology. The report is comparing calculated/theoretical values with experimental values, so the term “percentage difference” would be more accurate unless one value is clearly a true accepted value. Precise naming matters because it affects the interpretation of the discrepancy.

The student connects the qualitative analysis back to the research aim, which keeps the interpretation focused and relevant. This is a good analytical habit because it prevents the discussion from drifting into observations that are not tied to the question.

This conclusion is too general. The student should use the uncertainty ranges to identify which differences are actually meaningful and which are within uncertainty, rather than attributing most disagreement broadly to “uncertainties” and human error.

The student overstates the relationship here. The derived model is proportional to $ \sin\theta$,notdirectlyproportionalto$ heta$, so the discussion should describe a sine dependence or an increasing nonlinear trend rather than linear direct proportionality.

The method for slope uncertainty should be made more rigorous. Instead of choosing arbitrary point pairs, the student should draw valid steepest and shallowest acceptable lines through the uncertainty bars so the gradient uncertainty reflects the data properly.

The student is trying to interpret the graphs rather than merely describing them, which is a strong evaluative move. Linking the offset to reaction-time delay is plausible and shows an attempt to explain the pattern using experimental conditions.

The student should not call this relationship linear when the theory used in the report gives $a\propto \sin \theta$. The graphs may still show a positive trend, but the argument needs to match the actual model rather than forcing a linear description.

The evaluation identifies friction as a limitation, but the wording is too vague. The student should explain whether this is rolling resistance, surface roughness, or slipping friction, because each would affect the motion differently and lead to different improvements.

The student could strengthen the evaluation by linking this issue to the data numerically, for example by showing how a $0.01$ or $0.02$ s timing delay changes the calculated acceleration. That would make the critique more evidence-based and less general.

This conclusion is too confident given the discrepancies reported earlier. The student should reconcile the large percentage errors and the object-model mismatch before claiming reliability; otherwise the conclusion reads as more certain than the evidence supports.

The report includes a clear contents page, which helps the reader navigate the investigation efficiently. This supports readability and shows that the essay has a deliberate overall structure.

This section title suggests a discussion of earlier studies, but the content does not clearly provide prior experimental research. The student should either include genuine prior research or rename the section so the heading accurately reflects what is inside.

The document includes the expected components of an EE-style investigation, including a title, contents page, theory, method, analysis, evaluation, conclusion, and bibliography. This coherent sequencing makes the report easy to follow and supports the logical development of the argument.

The graphs would be easier to interpret if the student stated the key comparison directly in the figure note or accompanying text, such as which dataset is sphere/cylinder and what the trendline is meant to show. That would make the visual evidence more immediately useful.

The unit notation is not presented in standard scientific form. The student should write $\mathrm{m}{\mathrm{s}}^{-2}$ so the axis label is clearer and more conventional, especially in a physics report where precise notation matters.

This is an unsupported claim. Even a small angle uncertainty can still affect the gradient, so the student should justify the statement quantitatively or remove it if the uncertainty has not been properly evaluated.