Should You Take Physics and Chemistry Together?

A battery-powered car slows down even though its battery is still connected. Is the problem in the electrical circuit, the motor, the moving car, or the chemical reactions inside the battery?

Physics and Chemistry give you different tools for investigating the same system. Physics helps explain electrical energy, forces, and motion. Chemistry helps explain the reactions that allow a battery to store and release energy.

So, should you take Physics and Chemistry together for the HSC?

Yes, it can be an excellent combination, provided you genuinely enjoy both subjects and can manage the workload. They share important scientific skills, but their content, mathematical demands, and assessment requirements are different. Taking both is not automatically better than choosing one, and it does not guarantee a higher ATAR.

The decision comes down to three things: what you enjoy learning, what you might need for university, and how much work you can realistically manage across your other subjects.

01What do Physics and Chemistry have in common?

The strongest reason to study both subjects is that they develop many of the same scientific skills.

In both Physics and Chemistry, you need to:

• Develop questions and make predictions.
• Plan and conduct scientific investigations.
• Identify independent, dependent, and controlled variables.
• Collect measurements and organise experimental data.
• Construct and interpret graphs.
• Evaluate the reliability and validity of experimental results.
• Identify sources of uncertainty and experimental error.
• Use scientific models to explain observations.
• Communicate conclusions using appropriate scientific language.

These skills are particularly useful because they transfer between subjects.

A practical example: interpreting experimental data

Imagine you’re investigating two different experiments.

In Physics, you measure the displacement of a moving trolley at different times. You plot displacement against time and use the gradient to calculate velocity.

In Chemistry, you measure the volume of gas produced during a chemical reaction at different times. You plot gas volume against time and use the gradient to investigate the rate of gas production.

The graphs might look quite similar. Both require you to understand axes, gradients, measurements, and experimental uncertainty.

However, the physical meaning is different:

• In Physics, the gradient of a displacement-time graph represents velocity.
• In Chemistry, the gradient of a gas-volume-time graph represents the rate of gas production.

The mathematical skill transfers, but you still need to understand the separate scientific models behind each experiment.

This is the main advantage of studying both subjects: you become more comfortable working with experimental evidence, mathematical relationships, and scientific explanations.

However, shared skills don’t mean shared content.

02How are Physics and Chemistry different?

Physics and Chemistry investigate different aspects of the natural world.

Physics is largely concerned with understanding how physical systems behave. Chemistry focuses on the composition, structure, properties, and reactions of matter.

The distinction becomes clearer when you compare the questions each subject asks.

What you’ll study in Physics

The 2025 Physics 11-12 syllabus is organised into three Year 11 focus areas and four Year 12 focus areas.

Year 11:

• Fundamentals of mechanics
• Waves
• Electricity and magnetism

Year 12:

• Advanced mechanics
• Electromagnetism
• Nature of light
• Matter, energy and the cosmos

You’ll regularly work with mathematical relationships, equations, graphs, physical models, and experimental measurements.

For example, when studying mechanics, you might investigate how changing the net force on an object affects its acceleration. You’ll need to identify the relevant quantities, select an appropriate relationship, substitute values, and interpret the result.

What you’ll study in Chemistry

The 2025 Chemistry 11-12 syllabus also has three Year 11 focus areas and four Year 12 focus areas.

Year 11:

• Properties and structure of matter
• Quantitative chemistry
• Chemical reactions

Year 12:

• Equilibrium
• Acid-base reactions
• Organic chemistry
• Applying chemical ideas

Chemistry requires you to move between different representations of matter.

You might begin with an observation, explain it using a particle model, represent a reaction using a chemical equation, and then perform calculations to determine how much of a substance is involved.

For example, understanding a chemical reaction might require you to interpret a balanced equation, calculate the amount of reactant consumed, and explain why a particular product forms.

Chemistry is not a subject without mathematics. Quantitative chemistry involves calculations with quantities of substances, ratios, concentrations, and other numerical relationships.

Which subject is more mathematical?

Physics generally involves more direct mathematical modelling of physical systems.

You’ll need to become comfortable with:

• Rearranging equations.
• Working with ratios and proportional relationships.
• Interpreting gradients and areas under graphs.
• Using vectors and resolving quantities into components.
• Converting units and tracking significant figures.

Chemistry also involves substantial calculations, but its mathematical demands are different.

You’ll need to become comfortable with:

• Rearranging equations and working with ratios.
• Calculating quantities of substances.
• Using balanced chemical equations.
• Working with concentrations.
• Interpreting numerical experimental data.

A student who enjoys algebra but struggles with chemical equations might find Physics more natural. Someone who enjoys understanding particles, molecular structures, and chemical reactions might prefer Chemistry.

Neither subject is automatically easier. Your strengths and interests matter more than a general ranking of difficulty.

03What does taking both subjects mean under the 2025 syllabuses?

There is an important detail that students choosing subjects in 2026 and 2027 need to understand.

Although both replacement syllabuses are called the 2025 syllabuses, they do not begin teaching in the same year.

According to NESA:

• The new Physics syllabus begins implementation in 2027.
• The new Chemistry syllabus begins implementation in 2028.

This creates a transition period where students can study one new syllabus and one older syllabus at the same time.

Which syllabus applies to your cohort?

For example, if you’re starting Year 11 in 2027, you’ll study the new Physics syllabus but the existing 2017 Chemistry syllabus.

If you’re starting Year 11 in 2028, both subjects will use the replacement 2025 syllabuses.

This matters when choosing textbooks, finding practice questions, or using tutoring resources. The familiar Module 1-8 labels belong to the 2017 courses. The replacement syllabuses use focus areas instead.

You can check the implementation details directly through the official NESA Physics syllabus and NESA Chemistry syllabus.

04How much extra workload should you expect?

This is probably the most important practical consideration.

Physics and Chemistry are both 2-unit HSC courses. Under the 2025 syllabuses, each subject has 120 indicative hours in Year 11 and another 120 indicative hours in Year 12.

Taking both therefore means committing to:

• 4 units of science.
• 240 indicative course hours each year.
• Two separate sets of subject content.
• Two separate practical programs.
• Two sets of assessment requirements.
• Two depth-study requirements each year.

The depth studies deserve particular attention.

Both new syllabuses allocate 10 hours to depth studies within the 120 indicative course hours. Students must complete at least one depth study in Year 11 and at least one in Year 12 for each subject.

These hours are included in the 120-hour allocation. They are not additional hours on top of it.

What makes the workload difficult?

The difficulty isn’t necessarily that either subject is impossible on its own.

It’s that you’re managing two different types of learning simultaneously.

Physics often requires consistent problem-solving practice. If you don’t understand how a physical model connects to an equation, memorising formulas won’t get you very far.

Chemistry requires you to keep track of particles, chemical representations, reaction relationships, and calculations. Falling behind in one concept can make later topics harder to follow.

Both subjects also involve practical work and scientific communication.

You may have a Physics investigation to analyse during the same period that you’re preparing a Chemistry assessment. The skills might overlap, but the work still needs to be completed separately.

Before selecting both, ask your school about:

• The assessment calendar for each subject.
• When practical investigations and depth studies are scheduled.
• Whether major assessments are likely to overlap.
• Any timetable clashes between the two classes.
• The mathematical and scientific knowledge expected at the beginning of Year 11.

How can you prepare for both?

You don’t need to teach yourself the Year 11 courses before starting. However, strengthening a few foundational skills will make the transition easier.

For Physics, practise:

• Rearranging equations.
• Reading and interpreting graphs.
• Converting units.
• Working with scientific notation.
• Understanding basic forces, motion, and energy.

For Chemistry, revise:

• Atomic structure and the periodic table.
• Writing chemical formulae.
• Balancing chemical equations.
• Understanding ions and bonding.
• Using ratios and interpreting chemical information.

For both subjects, practise explaining your reasoning rather than simply writing down an answer.

05Do you need both subjects for university?

Not necessarily. This is where you need to distinguish between NESA requirements, school requirements, and university admission requirements.

They are three different things.

1. NESA requirements

NESA does not require every HSC student to study Physics or Chemistry.

Under the current HSC pattern-of-study rules, students must satisfactorily complete:

• At least 12 units in their Preliminary pattern of study.
• At least 10 units in their HSC pattern of study.
• 2 units of English.
• At least four subjects, alongside the other specified course requirements.

NESA also limits students to a maximum of 6 units of Preliminary Science courses and 7 units of HSC Science courses.

Physics and Chemistry together account for 4 science units, so taking both does not breach these limits.

The NESA ACE Rules explain the complete requirements.

Importantly, the 2025 NESA syllabus pages list no prerequisites for enrolling in either Year 11 course. The corresponding Year 11 course is required for progression into Year 12 Physics or Chemistry.

2. Your school’s requirements

Your school may have its own subject-selection guidelines.

For example, a school might recommend a particular level of Year 10 Mathematics or Science before students enrol in Physics. It might also have restrictions based on staffing, class sizes, or timetable availability.

These are school-level considerations, not universal NESA requirements.

If your school advises against taking both subjects, ask whether this is a formal enrolment restriction, an academic recommendation, or simply a timetable issue.

That distinction matters when deciding what to do next.

3. University prerequisites and assumed knowledge

This is where your future degree becomes relevant.

Universities can specify different types of HSC subject requirements.

For example, the current UNSW assumed knowledge guidance states that UNSW does not have formal subject prerequisites for its degrees, but individual degrees can specify assumed knowledge.

The University of Sydney’s admissions guidance explains that some courses have formal subject prerequisites, while others specify assumed knowledge.

These are university-specific policies. They are not statewide rules for NSW students.

If you don’t study a subject listed as assumed knowledge, you may still receive an offer, but you could find the first-year content more difficult. Universities may offer bridging courses to help fill those gaps.

However, a short bridging course is not equivalent to completing the full two-year HSC subject.

Check the exact degree and year of entry, rather than assuming every engineering, science, or health degree has the same requirements.

As at 8 November 2026, UAC’s Steps to Uni for Year 10 Students (2026) provides useful explanations of these requirements. Its institution listings refer to courses planned for 2026, however, so they should not be treated as confirmed admission requirements for students applying in 2028 or 2029.

If you’re starting Year 11 in 2027 and expect to enter university in 2029, check the relevant university’s course information for that entry year as it becomes available.

For a more detailed explanation, read tutorgum’s guide to What Is the Difference Between Assumed Knowledge and a Prerequisite?.

06Will taking both subjects improve your ATAR?

You might have heard that Physics scales particularly well, or that taking multiple science subjects gives you an ATAR advantage.

Be careful with this reasoning.

UAC calculates the NSW ATAR using scaled marks from 10 units of HSC courses:

• The best 2 units of English.
• The best 8 units from your remaining courses.

Scaling allows marks from different HSC courses to be compared. It reflects the overall academic performance of students taking each course, rather than giving every student a fixed bonus for selecting a particular subject.

Physics has traditionally scaled strongly. However, that does not mean every Physics student receives a better ATAR than they would by studying another subject.

Scaling statistics change from year to year, and your own HSC performance still matters.

Taking Physics and Chemistry together does not create an automatic ATAR bonus. Nor does it guarantee that both courses will contribute to your final ATAR aggregate if you study more than 10 units.

You should choose subjects based on your interests, demonstrated abilities, and future plans rather than trying to predict which combination will scale best.

You can read UAC’s explanations of how your ATAR is calculated and frequently asked questions about scaling.

07How should you decide whether to take both?

There isn’t one subject combination that works for every student.

However, there are some useful indicators.

Taking both is a good option if:

• You genuinely enjoy both physical science and chemical science.
• You like solving mathematical problems and understanding scientific models.
• You are interested in pathways where both subjects provide useful preparation.
• You are comfortable managing practical investigations and independent study.
• Your school can accommodate both subjects without major timetable problems.
• You can maintain a sensible workload across your entire HSC pattern.

Consider taking only one if:

• You strongly prefer one subject’s content over the other’s.
• You’re choosing the second subject mainly because of scaling.
• You struggle to maintain consistent study habits across several demanding subjects.
• The additional workload would compromise your performance in other courses.
• Your intended university pathway only requires or assumes knowledge of one, and you have a stronger reason to select another subject.

What if you don’t know what you want to study after school?

You don’t need to have your university degree decided in Year 10.

Studying both sciences can keep several science and technology pathways open, but taking both is not the only way to preserve your options.

Start by identifying the types of problems you enjoy solving. Then investigate the subjects that will help you develop those skills.

If you’re still working out your full HSC pattern, tutorgum’s guide to How Many Units Should You Take in Year 11? is a useful next step.

The goal is to build a combination that gives you enough flexibility without creating a workload you cannot sustain.

08Questions and solutions

Question 1

Daniel enjoys solving mechanics problems, working with equations, and investigating how objects move. However, he finds chemical formulae and reactions less interesting.

His friends recommend taking Physics and Chemistry together because they are closely related sciences.

Should Daniel automatically take both?

Solution 1

No. Daniel has a clear reason to consider Physics, but he hasn’t established a reason to study Chemistry.

The two subjects share scientific investigation skills, but their content is substantially different.

Physics focuses on areas such as mechanics, waves, and electromagnetism. Chemistry focuses on the structure of matter, chemical reactions, and chemical systems.

Enjoying Physics does not automatically mean Daniel will enjoy Chemistry.

He should investigate the Chemistry course content before making a decision. If he finds chemical reactions and molecular structures interesting, taking both could be worthwhile.

If he is only considering Chemistry because his friends say the subjects belong together, he should reconsider.

The strongest subject combinations are built around genuine interest and academic suitability, not the assumption that certain subjects must be taken as a pair.

Question 2

A student completes two investigations.

In Physics, they measure the displacement of a moving object over time.

In Chemistry, they measure the volume of gas produced during a reaction over time.

Both investigations involve plotting a graph and calculating its gradient.

Explain two scientific skills that transfer between the subjects and why the gradient has a different physical meaning in each investigation.

Solution 2

The transferable skills are graph interpretation and experimental data analysis, but the gradients represent different quantities.

In the Physics investigation, the student plots displacement against time.

The gradient represents velocity:

\[ v=\frac{\Delta x}{\Delta t} \]

where:

• \(v\) is velocity in metres per second.
• \(\Delta x\) is the change in displacement in metres.
• \(\Delta t\) is the change in time in seconds.

In the Chemistry investigation, the student plots gas volume against time.

The gradient represents the rate of gas production:

\[ \text{Rate}=\frac{\Delta V}{\Delta t} \]

where:

• \(\Delta V\) is the change in gas volume.
• \(\Delta t\) is the change in time.

The student uses the same general mathematical technique, but the units and scientific interpretation are different.

Both investigations also require careful measurements, controlled variables, and an evaluation of experimental uncertainty.

This is why studying both subjects can strengthen your scientific reasoning. You repeatedly apply similar skills to different scientific problems.

Question 3

A school tells a student that they cannot enrol in Year 11 Physics and Chemistry together unless they achieve a particular result in Year 10 Science.

The student believes NESA requires a specific Year 10 Science result before allowing students to study both subjects.

Is the student’s understanding correct? Explain the difference between the NESA requirements and the school’s decision.

Solution 3

No. A school’s selection guideline should not be confused with a statewide NESA prerequisite.

The 2025 NESA Physics and Chemistry syllabus pages both list no formal prerequisites for their respective Year 11 courses.

This means NESA does not specify a universal Year 10 Science mark that every student must achieve before enrolling in either course.

However, the school may have its own selection policy or academic recommendations.

The student should ask the school whether the stated result is:

• A formal school enrolment requirement.
• A recommendation based on the expected difficulty of the course.
• A guideline that can be reconsidered after speaking with the relevant head teacher.

The student should also confirm that both classes fit their timetable.

The distinction is important: NESA establishes the statewide course requirements, while schools make practical decisions about delivering the subjects and managing enrolments.

Question 4

A student has 12 units in their HSC pattern and is considering taking Physics and Chemistry.

They argue that taking both must improve their ATAR because Physics traditionally scales well and Chemistry provides another set of scaled marks.

Explain why this conclusion is not necessarily correct.

Solution 4

Taking both subjects does not guarantee a higher ATAR because UAC uses scaled marks from the best 10 units, not every unit a student studies.

The NSW ATAR calculation uses:

\[ \text{ATAR aggregate} = \text{Best 2 English units} + \text{Best 8 other scaled units} \]

If a student studies more than 10 units, not every course necessarily contributes to the final aggregate.

Furthermore, scaling changes each year. It depends on the academic performance profile of students taking each course.

A subject’s historical scaling performance does not guarantee the same outcome for an individual student.

The tempting argument is that two traditionally strong science subjects must produce a better aggregate than one.

However, this ignores the student’s actual performance and the way UAC selects the units used in the calculation.

A student who achieves stronger results in another subject may be better served by studying that subject instead.

The correct decision is to choose Physics and Chemistry if they suit the student’s interests, abilities, and future plans, rather than treating them as an ATAR strategy.

Question 5

Amira is choosing her HSC subjects in late 2026. She will start Year 11 in 2027, sit the HSC in 2028, and apply for university entry in 2029.

She is interested in both engineering and medicinal chemistry.

Her family makes three claims:

1. Both subjects use the 2025 syllabuses because the new syllabuses were released in 2025.
2. A university course that lists Chemistry as assumed knowledge requires her to study Chemistry in the HSC.
3. Taking both Physics and Chemistry is the safest way to guarantee access to both university pathways.

Her school can only timetable one of the two subjects for her.

Using the NESA implementation dates and university admission terminology, evaluate these claims. What should Amira do before making her final subject selection?

Solution 5

None of the three claims is fully correct. Amira needs to distinguish syllabus implementation, university admission requirements, and school timetable restrictions before choosing.

Start with the syllabus implementation dates.

NESA has different implementation years for the replacement courses:

• Physics 11-12 (2025) begins implementation in 2027.
• Chemistry 11-12 (2025) begins implementation in 2028.

Therefore, Amira will study:

• The new 2025 Physics syllabus.
• The existing 2017 Chemistry syllabus.

She will not study both replacement syllabuses during Year 11.

The release year of a syllabus does not determine when students begin studying it. Its implementation date does.

Next, consider the university’s use of the term assumed knowledge.

Assumed knowledge is not the same as a formal course prerequisite.

If Chemistry is listed as assumed knowledge, Amira may still be eligible for an offer without having studied it. However, the university expects her to understand the relevant material when she begins the degree.

She might need additional preparation or a bridging course.

If Chemistry is listed as a formal course prerequisite instead, the situation is different. She must satisfy that requirement to be considered for admission.

Finally, consider the claim that taking both subjects guarantees access to both pathways.

This is not correct.

Universities set their own course requirements. One engineering degree might assume Physics, another might recommend Chemistry, and a medicinal chemistry degree might assume Chemistry and particular mathematical knowledge.

There is no universal NSW university requirement that students must take both Physics and Chemistry.

The school timetable is another separate issue. Amira cannot assume that both subjects will be available simply because NESA permits them.

The best next step is to investigate the exact university courses she wants to keep open and check their 2029 entry requirements.

She should classify each subject requirement as a formal course prerequisite, a subject prerequisite, assumed knowledge, or recommended study.

If one course has a formal prerequisite and the other only has assumed knowledge, the formal prerequisite has a different consequence for admission. She should then consider whether alternative preparation or bridging courses could address the assumed knowledge gap.

She should also speak with her school about whether the timetable restriction is fixed and whether another arrangement is possible.

The important point is that taking both subjects is not automatically the safest decision. It depends on the actual requirements of the courses she wants to study, the alternatives available, and the academic workload she can manage.

This is a much stronger basis for subject selection than choosing two sciences simply because they seem like a natural combination.

Once you’ve decided which subjects suit your goals, the next step is to check how they fit into your complete HSC unit pattern and whether your overall workload is realistic.