IB Physics SL Extended Essay Example

The topic is communicated clearly and with purpose: the student identifies a specific comparison and frames it as a research question rather than a broad theme. This gives the investigation a recognisable direction and makes the later calculations easier to follow.

The word “efficiency” is not defined with enough precision here. The student mixes v, transfer time, and propellant mass as if they measure the same thing, but they can lead to different conclusions. The investigation would be clearer if one primary efficiency criterion were stated and the others treated as secondary comparisons.

Consider tightening the hypothesis by naming the exact efficiency metric, the expected crossover trend, and the orbital-ratio range being tested. That would make the claim easier to verify and would align the introduction, method, and conclusion more closely.

What would change in the argument if the student ranked these dependent variables by importance instead of treating them equally? Asking this would help decide whether the comparison is really about fuel use, time, or mission practicality.

The variable description is not fully accurate: the later table gives $48,700\mathrm{kg}$ as the wet mass, while this sentence says dry mass is kept constant. The method needs consistent definitions so that the propellant calculations are reproducible and physically meaningful.

The methodology is appropriate for the research question because it combines orbital-mechanics equations with computational comparison across multiple cases. This shows informed selection of a method suited to a theoretical physics investigation rather than an experimental one.

This assumption is reasonable for a first model, but the method does not yet show how sensitive the results are to that simplification. A brief justification or a sensitivity check would strengthen the completeness of the approach, especially for real mission cases that are not perfectly circular.

The method would be stronger if the student included a short worked example or the actual code logic used for one transfer case. That would make the calculation process more transparent and allow the reader to judge whether the outputs were generated consistently.

This source does not appear to be relevant evidence for the claim being made about Newtonian gravitation and orbital motion. The student should replace it with a source that directly supports celestial mechanics or orbital transfer physics.

This value is incorrect; the gravitational constant should not be $6.617\times 10^{-13}$. Because this constant underpins the derivations that follow, the error weakens the accuracy of the orbital mechanics throughout the background section.

The student applies the Hohmann-transfer concept coherently by linking the first and second impulses to the overall v requirement. This shows solid understanding of how the transfer ellipse is decomposed into physically meaningful stages.

It would strengthen the background if the student briefly distinguished between total v and propellant mass explicitly before the calculations begin. That would make the later comparison between the two transfer methods easier to interpret.

The table labels the spacecraft mass inconsistently with the later calculations. If this value is being used as the initial mass in the rocket equation, it should be identified as wet mass or launch mass instead of dry mass.

The terminology is not fully controlled here: “mass that is used to burn the velocity” is not standard physics phrasing. The student should use precise terms such as propellant mass, mass ratio, or m so the concepts match the equations being used.

The student presents comparative numerical results in a structured way, which makes the later analysis possible. Using a matching table for each transfer type is a strong choice because it allows the reader to compare values directly across the same orbital cases.

This conclusion contradicts the student’s own preceding sentence that bi-elliptic generates a higher transfer time in all orbital ratios. The argument needs to be checked for logical consistency before the results can be considered reliable.

The explanation here is physically questionable: a very large apoapsis does not automatically make the first burn small for a small transfer. The student should re-check the bi-elliptic equations and verify that the interpretation matches the computed values before using this as a causal explanation.

The evaluation is too vague here. The student should specify which quantity is sensitive, by how much, and whether that sensitivity is due to the rocket equation, the chosen $r_3$ value, or a numerical input issue.

The evaluation would be stronger if the student explained how a finite-burn model would change the computed outputs in this specific investigation. A brief comparison to the ideal impulsive model would make the limitation more analytical than descriptive.

This is a strong evaluative point because it identifies a specific modelling choice that can distort the results. The student also connects that limitation to the observed contradiction between the v graph and the mass graph, which shows real critical reflection.

The section numbering is inconsistent here because section 2.6 is missing from the contents. The student should check the sequence of headings so the structure is fully conventional and easier to follow.

The report follows a clear academic structure, beginning with an introduction and continuing through background, methodology, analysis, evaluation, conclusion, and references. This organisation helps the reader navigate the investigation and supports the overall clarity of presentation.

The table numbering is inconsistent because the same table number is reused for different datasets later in the report. Unique and sequential table labels would make cross-referencing much clearer for the reader.

The heading text in the results tables is not fully consistent with the underlying ratios used later, where the numeric values appear to be expressed as $r_2/r_1$ despite the label here. The student should align the table headings with the actual quantity being reported.

The graphs would communicate trends more clearly if the student narrowed the x-axis range or used a logarithmic scale for the very wide orbital-ratio spread. That would reduce compression at the low end and make the crossover behaviour easier to see.

The inclusion of separate graphs for each dependent variable is effective presentation because it helps the reader see different dimensions of the comparison instead of forcing all trends into one figure. That makes the results easier to interpret.