Grade 10 Physical Sciences · Mechanics

Identify variables in an investigation

Name the independent, dependent and controlled variables in an experiment (in a test of temperature on reaction rate, temperature is independent).

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Independent, Dependent and Controlled VariablesScience Ready

Identify Variables in a Scientific InvestigationMooMooMath and Science

Physical Sciences Practical investigation/experiments for grade 10-12Miss Martins Maths and Science

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Question 5.2 · May/June 2022 · Paper 2 · National (DBE) · 2 marks

Learners use the reaction of

MgCO_{3}

(s) with EXCESS dilute HC

ℓ

(aq) to investigate the relationship between temperature and the rate of a chemical reaction.

The balanced equation for the reaction is:

MgCO_{3} (s) + 2 HC ℓ (aq) \to MgC ℓ_{2} (aq) + CO_{2} (g) + H_{2} O (ℓ)

The results obtained are represented in the graph below. Diagram for this question

5.2 State TWO conditions that must be kept constant during this investigation.(2)

Work it out on paper first. Then mark yourself with the official memo, one tick at a time.

More past paper questions: identify variables in an investigation

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3. Question 9.2.2 · November 2025 · Paper 1 · Provincial · 2 marks
Learners investigate the relationship between current in a conductor and the potential differences across the ends of the conductor. The graph below is obtained from their investigation.
9.2 Write down the:
9.2.2 Control variables for this investigation(2)
Show the memo (2 ticks)Memo
1. ✓
  First control variableTemperature (accept resistance)
  1 mark · Identify variables in an investigation
2. ✓
  Second control variableLength of conductor (or thickness of conductor)
  1 mark · Identify variables in an investigation
4. Question 4.2.2 · November 2025 · Paper 2 · Provincial · 2 marks
A group of learners investigated the relationship between the pressure and volume of a certain gas. The graph of the pressure versus inverse of volume was obtained from the data in the investigation.
4.2 From the investigation write down:
4.2.2 TWO controlled variables for this investigation(2)
Show the memo (2 ticks)Memo
1. ✓
  First controlled variableTemperature
  1 mark · Identify variables in an investigation
2. ✓
  Second controlled variableAmount of gas
  1 mark · Identify variables in an investigation
5. Question 6.2.1 · November 2025 · Paper 1 · National (DBE) · 1 mark
An investigation is performed to determine the relationship between the velocity of a moving sound source and the frequency of the sound detected.

The siren of an ambulance produces sound with a constant frequency. The ambulance, with its siren on, moves towards a stationary sound detector (Part A) and away from the stationary sound detector (Part B) at constant velocities. The experiment is repeated for different velocities of the ambulance. The detected frequency is measured for EACH velocity. The results obtained are shown in the graph below.
6.2 For this experiment, write down:
6.2.1 The independent variable(1)
Show the memo (1 tick)Memo
1. ✓
  Independent variableVelocity/speed/ $v_{s}$ of the ambulance/source
  1 mark · Identify variables in an investigation
6. Question 3.1.3(a) · May/June 2025 · Paper 2 · National (DBE) · 1 mark
3.1 The boiling points of straight chain aldehydes and straight chain carboxylic acids are compared. The table below shows the results obtained.

Answer the questions that follow.
3.1.3 For INVESTIGATION 2:
3.1.3(a) Write down the controlled variable.(1)
Show the memo (1 tick)Memo
1. ✓
  Controlled variableHomologous series
  1 mark · Identify variables in an investigation

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