AQA A-Level Physics Paper 1, June 2022: Question 7
1 mark · Medium difficulty · Multiple Choice
Identify which two physical quantities have the base unit kg m^2 s^-2 from the given multiple-choice options.
Practise this questionQuestion
Question text
07 Which two quantities have the base unit kg m2 s−2?
[1 mark]
A kinetic energy and momentum
B kinetic energy and Young modulus
C work done and the moment of a couple
D work done and pressure
Mark scheme
Show the mark scheme
Question Key Answer
07 C (AO1) work done and the moment of a couple
How to answer it
Identifying Physical Quantities from Base Units
What this question tests
This question assesses your ability to recall and derive SI base units for derived physical quantities (AO1). You must demonstrate fluency in breaking down equations into fundamental quantities (kg, m, s, A) rather than relying on memorised composite units.
Determining the Correct Quantity Pair
✅ Correct Answer: C
work done and the moment of a couple
Both quantities share the base unit kg m² s⁻² .
💡 Key Knowledge
- Work Done: Force × displacement ( F × s ). Force has base units kg m s⁻² , multiplied by metres gives kg m² s⁻² (equivalent to Joules).
- Moment of a Couple: Force × perpendicular distance between the lines of action ( F × d ). Dimensionally identical to work done or torque ( N m ).
🧠 Exam Technique
Don't waste time checking every single option thoroughly if you can eliminate distractors quickly. Check equations using defining formulas you know by heart, substituting base units step-by-step.
❌ Common Errors
- Confusing momentum ( kg m s⁻¹ ) with kinetic energy or work done.
- Treating Young modulus (which has units of pressure/stress, N m⁻² or kg m⁻¹ s⁻² ) as an energy quantity.
Topics
Physics · 3.1 Measurements and their errors · 3.4 Mechanics and materials
Question and mark scheme from the AQA A-Level Physics examination, Paper 1, June 2022. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.