# How to Answer 'Compare' Physics Questions | HSC Physics Key Verb Series Part 2

'Compare' Physic question types can be tricky to answer correctly. Learn how to answer 'compare' physics questions in your next exam effectively with Learnable's ToC Framework TM

## Answering ‘compare’ long response questions

Students find ‘compare’ Physics questions tricky to answer. Most students struggle to identify the comparative features and provide irrelevant and non-comparative response.

‘How to answer ‘compare’ Physics questions’ is a comprehensive guide for students on how to develop a structured scientific response that is specific, relevant and comparative.

## Types of ‘compare’ long response questions in the HSC Physics Exam

Compare physics questions are perceived to be relatively easy to answer. But it’s also the question type students can lose marks easily without knowing.

There is always one or more ‘compare’ question in the HSC Physics Exam.

There are two main types of compare questions asked in HSC Physics exams:

1. Compare qualitatively {………………}
2. Compare quantitatively {………………}

### Examples of ‘compare’ questions in Physics exams

Marks allocated for an ‘compare’ long response question can vary from 2 to 6 marks. Examples of ‘compare’ questions with different marks are listed below.

 Question Marks Question 1 (2016 HSC Q25)Compare qualitatively the relationship between force and distance in the graphs.Source: NSW Education Standards Authority 2 Question 2 (2019 HSC Q28)A metal loop, WXYZ is connected to a battery and placed in a uniform magnetic field. A current flows through the loop in the direction shown. The loop is then allowed to rotate by 90° about the axis PQ.Compare the forces acting on WX and XY before and after this rotationSource: NSW Education Standards Authority 3 Question 3 (2018 HSC Q21)(a) Compare the force of gravity exerted on the moon by Earth with the force of gravity exerted on Earth by the moon. (b) The acceleration due to gravity on the moon is 1.6 m s–2 and on Earth it is 9.8 m s–2. Quantitatively compare the mass and weight of a 70 kg person on the moon and on Earth.Source: NSW Education Standards Authority 4 Question 4Compare the operations of a brushed DC electric motor and an AC induction motor. 5

## What is the process for answering ‘compare’ Physics questions?

To answer ‘compare’ physics questions, you must first understand the meaning of the verb, ‘compare’.

The NSW Education Standards Authority defines ‘compare’ as “show how things are similar or different.”

When answering ‘compare’ questions, students are required to show similarities and/or differences between two or more things.

Compare requires similarities and/or differences whereas ‘contrast’ requires differences only.

One of the ways to show similarities and/or differences using Learnable’s ToC FrameworkTM  to construct a specific and relevant response.

### Learnable’s ToC FrameworkTM

The ToC FrameworkTM or Table of Comparison helps you compare similarities and/or differences between two or more things in a structured manner and meet the marking criteria for ‘compare’ questions.

A ToC for comparing 2 objects is shown below.

 Features Object 1 Object 2 Step 1: Identify a feature for comparison Step 2a: Provide a qualitative or quantitative comparative detail based on feature identified. Step 2b: Provide a qualitative or quantitative comparative detail based on feature identified. Feature 2 Feature 3

A ToC for comparing 3 objects is shown below.

 Object 1 Object 2 Object 3 Feature 1 Feature 2 Feature 3

When comparing 2 objects, you need to construct a 3 column ToC. When comparing 3 objects, you need to construct a 4 column ToC.

## Sample ‘compare’ Physics questions and answers using the ToC FrameworkTM

Let’s apply Learnable’s ToC Framework to answer the two types of ‘compare’ Physics questions.

1. Compare qualitatively {……………….}
2. Compare quantitatively {……………….}

### Question 1 (2018 HSC Q21)

(a) Compare the force of gravity exerted on the moon by Earth with the force of gravity exerted on Earth by the moon.  (2 marks)
(b) The acceleration due to gravity on the moon is 1.6 m s–2 and on Earth it is 9.8 m s–2. Quantitatively compare the mass and weight of a 70 kg person on the moon and on Earth. (2 marks)

### Solution to Question 1(a)

This is qualitative comparative question.

Step 1: Identify the features that require a direct comparison.

 Feature Force of gravity on the moon by Earth Force of gravity on Earth by the moon Magnitude of the force Direction of the force

Step 2: Provide a qualitative or quantitative comparative detail for each feature identified.

 Feature Force of gravity on the moon by Earth Force of gravity on Earth by the moon Magnitude of the force Equal in magnitude Equal in magnitude Direction of the force Different Different

Step 3: Construct a specific, relevant and comparative response.

A sample response to the question using the ToC Framework is shown below.

The force of Earth on the moon is equal in magnitude to the force of the moon on Earth, but in the opposite direction.

### Solution to Question 1(b)

Part (b): This is quantitative comparative question.

Step 1: Identify the features that require a direct comparison.

 Feature On the moon On Earth Mass of 70 kg person Weight of 70 kg person

Step 2: Provide a qualitative or quantitative comparative detail for each feature identified.

 Feature On the moon On Earth Mass of 70 kg person Mass does not change due to gravity: 70 kg. Mass does not change due to gravity: 70 kg. Weight of 70 kg person Weight on the Moon:W= mg = 70 x 1.6 =112 N Weight on Earth:W= mg = 70 x 9.8 =686 N

Step 3: Construct a specific, relevant and comparative response.

Quantitative comparison of the mass and weight of a 70 kg person on the moon and on Earth is given in the table below.

 Feature On the moon On Earth Mass of 70 kg person Mass does not change due to gravity: 70 kg. Mass does not change due to gravity: 70 kg. Weight of 70 kg person Weight on the Moon:W= mg = 70 x 1.6 =112 N Weight on Earth:W= mg = 70 x 9.8 =686 N

The table of comparison in Step 2 can be presented as the answer. In fact the HSC Marketing Committee recommends that students use a table for answering ‘compare’ Physics questions. 