# Hands-On-Physics ELECTRICITY

## A Guide for Student Defined Extensions

Scientific investigations generally focus on the cause/effect relationship between two variables. Change one aspect of the situation and see how another is effected. Deciding what variables to investigate is a major part of defining the problem. For example; you might be interested in the effect of the wheels on Aircart motion. To make this a scientific study you would have to decide what you want to study about wheels; the number of wheels, their diameter, their width, the bearings, or some other wheel feature. Next you must decide what effect you'd like to observe as you change the wheels; the time for the Aircart to travel 1 meter, the average speed in 50 cm, the distance it travels in 5 seconds, its acceleration, or some other aspect of its motion.

Once you have chosen the independent variable (cause) and the dependent variable (effect), you can decide how the change the independent variable (like the number of wheels) and how to measure the dependent variable (like the distance traveled). It is a good idea to set up a table for recording measurements as you change the independent variable. A graph helps with the visualization of the relationship and may lead to a mathematical model.

Plan your extension so your report will have diagrams, tables, graphs, calculations, and equations.

Talk through your ideas with your teacher and make a plan before you begin to experiment. Once experimentation starts you will probably want to revise your original plan.

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