AQA A-Level Physics Paper 1, November 2020: Question 6

1 mark · Easy difficulty · Multiple Choice

Identify the correct statement regarding mechanical power from four multiple-choice options.

Practise this question

Question

A multiple-choice question numbered 0 6 with the heading 'Mechanical power' and worth [1 mark]. It asks which statement about mechanical power is correct, with options A (is a vector quantity), B (is measured in J), C (has base units of kg m^2 s^-3), and D (can be calculated from force * distance moved), each with an associated selection box.
Question text

06 Mechanical power

[1 mark]

A is a vector quantity.

B is measured in J.

C has base units of kg m2 s−3.

D can be calculated from force × distance moved.

Mark scheme

Show the mark scheme A simple table showing the mark scheme key for question 06, indicating that the correct answer is C.

Question Key

06 C

How to answer it

Mechanical Power Properties

AQA A-Level Physics • Question 06 • 1 Mark

What this question tests

This question assesses your understanding of physical quantities, specifically mechanical power. It tests your ability to recall or derive base SI units, distinguish between scalar and vector quantities, recognize appropriate units of measurement, and identify fundamental definitions relating to energy transfer and work done.

Question 06

Select the correct statement regarding mechanical power from the options below:

  • A is a vector quantity.
  • B is measured in J.
  • C has base units of kg m² s⁻³.
  • D can be calculated from force × distance moved.
Awarded: [1 mark] for selecting option C.

✅ Correct Answer: C

Power has base units of kg m² s⁻³ .

Reasoning: Power ($P$) is defined as work done ($W$) per unit time ($t$), or energy transferred per unit time ($P = E / t$). Energy has the same base units as work done ( kg m² s⁻² ). Dividing by time ( s ) yields kg m² s⁻³ .

💡 Key Knowledge

  • Scalar vs Vector: Power is a scalar quantity because it describes the rate of energy transfer without any specific direction. Statement A is false.
  • Units: Power is measured in watts (W) or joules per second (J s⁻¹), not just joules (J). Statement B confuses power with energy or work done.
  • Definitions: Force × distance moved is the definition of work done (or energy transferred), not power. Statement D misses the division by time.

🧠 Exam Technique

When evaluating multiple-choice questions involving units, use dimensional analysis or derive base units step-by-step on your data booklet formula sheet if you are unsure.

❌ Common Errors

  • Confusing power with work done or energy (choosing option B or D).
  • Failing to divide by time when converting derived units into SI base units.

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, November 2020. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.