Give one variable that should have been a control variable in this investigation.
How to approach this question
A control variable is something you keep the same to ensure a fair test. The investigation is about how acceleration depends on force (F=ma). To investigate the relationship between F and a, what other quantity in the equation must be kept constant?
Full Answer
Mass of the trolley
In this experiment, the student is investigating the relationship between resultant force (the independent variable) and acceleration (the dependent variable). According to Newton's Second Law, F = ma. To isolate the relationship between F and a, the mass (m) of the system must be kept constant. If the mass of the trolley were to change during the experiment, it would not be a fair test, as both force and mass would be affecting the acceleration.
Common mistakes
✗ Naming the independent variable (force) or dependent variable (acceleration).\n✗ Naming a factor that is not relevant, like "room temperature".
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