The Nature of Science 4.3 Methods of investigation
When scientists want to investigate they need to choose the most suitable method of investigation. The methods that we will examine are: controlled experiments, observational experiments, modelling and research.
1. A controlled experiment A squash player observes that the squash ball seems to get bouncier as the game continues. He also notices that the ball seems to get warmer. Based on this observation he forms a hypothesis that the bounce of the squash ball is affected by its temperature. This hypothesis can be tested by doing a controlled experiment. A controlled experiment would be suitable because we could control the temperature and measure the bounciness. The hypothesis is that the increase in temperature causes the ball to become bouncier. Based on this hypothesis, there are two variables – temperature (the cause variable) and bounce (the effect variable). Both variables must be measured as carefully as possible.
Fig. 4 Why does a squash ball get bouncier as the game progresses?
This experiment could be conducted as follows: Hypothesis: The bounce of the squash ball is affected by its temperature. Type of data: Quantitative – measure temperature of ball and height of bounce. Method 1. Drop a squash ball from 100 cm above the ground. 2. Measure how far it bounces back up. 3. Change the temperature of the ball and measure the bounce again.
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Fig. 5 Measuring how far a squash ball bounces back up
