AQA AS Level Physics Paper 2, November 2021: Question 16

1 mark · Easy difficulty · Multiple Choice

Identify the correct statement regarding momentum and kinetic energy conservation in an inelastic collision between two isolated objects.

Practise this question

Question

Multiple choice question 16 asking what is true for an inelastic collision between two isolated objects. Option A states both total momentum and total kinetic energy are conserved. Option B states neither total momentum nor total kinetic energy is conserved. Option C states only total kinetic energy is conserved. Option D states only total momentum is conserved.
Question text

16 What is true for an inelastic collision between two isolated objects?

[1 mark]

A Both total momentum and total kinetic energy are conserved.

B Neither total momentum nor total kinetic energy is conserved.

C Only total kinetic energy is conserved.

D Only total momentum is conserved.

Mark scheme

Show the mark scheme The mark scheme shows question 16 has the correct answer D: Only total momentum is conserved.

16 D Only total momentum is conserved.

How to answer it

Question 16: Properties of Inelastic Collisions

What this question tests

This question assesses your fundamental understanding of conservation laws during collisions, specifically distinguishing between elastic and inelastic collisions for isolated systems.

Question 16

Multiple Choice Component [1 mark]

✅ Correct Answer: D

Only total momentum is conserved. In any collision between isolated objects (where no external forces act), total momentum is always conserved. However, in an *inelastic* collision, kinetic energy is not conserved—some kinetic energy is converted into other forms, such as thermal energy or sound.

💡 Key Knowledge

  • Momentum: Always conserved in all collisions for isolated systems due to Newton's third law.
  • Kinetic Energy: Conserved only in perfectly *elastic* collisions. In *inelastic* collisions, total kinetic energy decreases.

🧠 Exam Technique

Eliminate options systematically. You know momentum is always conserved for isolated objects, which immediately rules out options B and C. Since kinetic energy is not conserved in an inelastic collision, option A is incorrect, leaving D as the only valid choice.

❌ Common Errors

Students sometimes confuse "inelastic" with "no conservation laws apply at all" (choosing B) or mistakenly assume kinetic energy is always conserved in every collision scenario.

Examiner Note: This is a straightforward recall and comprehension question designed to test core mechanics definitions. Full marks are awarded simply by selecting option D.

Topics

Physics · 3.4 Mechanics and materials

Question and mark scheme from the AQA AS Level Physics examination, Paper 2, November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.