A student fixes a propeller to an electric motor that is powered by a $0$ to $12\,\text{V}$ d.c. power supply, as shown in Fig. 4.1. The air set in motion by the propeller exerts a force on the balance. Plan an experiment to investigate how this force changes with the voltage of the power supply. The apparatus available is: an electric motor, an electronic balance, a power supply, a propeller, a voltmeter. You may also use other apparatus and materials that are normally found in a school laboratory.
(main)[6]
Your plan should:
- give a brief account of how the investigation will be carried out
- state the main variables that need to be controlled
- draw a table, with column headings, to show how the readings will be presented (you do not need to put any readings in the table)
- explain how the readings will be used to reach a conclusion.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Adjust the voltage and note the balance reading” …