A Level Physics Practice Exam

How can you show that quantities in interactions are conserved?

1. By listing all particles involved

2. By showing the quantity in brackets next to the particle

3. By calculating the energy difference

4. By ignoring irrelevant quantities

The correct answer is: By showing the quantity in brackets next to the particle

The option that indicates showing the quantity in brackets next to the particle pertains to visualizing and explicitly denoting what quantities are being conserved in a given interaction. This approach clarifies which specific conservation principle is being applied, such as conservation of momentum, charge, or energy. When we list quantities alongside each particle, we make it clear what the initial and final values are for each relevant quantity involved in the interaction. This visual representation allows for an easy comparison, facilitating the understanding that these quantities remain constant before and after the interaction, assuming no external forces come into play. While listing all particles involved may provide context to an interaction and calculating energy differences may seem related to energy conservation, these methods do not explicitly demonstrate conservation principles in a clear, comparative manner. Ignoring irrelevant quantities is also not a method that shows conservation, but rather a tactic to simplify the analysis without addressing what is actually conserved.