Review of the Scientific Method

MFMcGrawChap0-Scientific Method-Revised 5/5/102 CONCEPT - an abstract or generic idea generalized from particular instances. FACT - something that has actual existence. For example space exploration is now a fact. HYPOTHESIS implies insufficient evidence to provide more than a tentative explanation. For example, a hypothesis explaining the extinction of the dinosaurs. LAW implies a statement of order and relation in nature that has been found to be invariable under the same conditions. For example, the law of gravitation>. THEORY - a plausible or scientifically acceptable general principle or body of principles offered to explain phenomena. For example the wave theory of light> Scientific Method

MFMcGrawChap0-Scientific Method-Revised 5/5/103 Scientific Method Recognize a question or a puzzle - such as an unexplained fact. Do some research and make an educated quess - a hypothesis - that mght resolve the puzzle. Predict consequences of the hypothesis. Perform experiments or make calculations to test the predictions. Formulate the simplest general rule that organizes the three main ingredients: hypothesis, predicted effects, and experimental findings. Source: Conceptual Physics, Hewitt, 11th Ed., p.7

MFMcGrawChap0-Scientific Method-Revised 5/5/104 Scientific Method The scientific method is a way to ask and answer scientific questions by making observations and doing experiments. The steps of the scientific method are to: o Ask a Question o Do Background Research o Construct a Hypothesis o Test Your Hypothesis by Doing an Experiment o Analyze Your Data and Draw a Conclusion o Communicate Your Results It is important for your experiment to be a fair test. A "fair test" occurs when you change only one factor (variable) and keep all other conditions the same.

MFMcGrawChap0-Scientific Method-Revised 5/5/105 Scientific Method

MFMcGrawChap0-Scientific Method-Revised 5/5/106 Observation and Measurement How do you know whether the earth is flat or round? Is there any evidence that we can see from here? Where would be the best place to find this evidence? Hypothesis: the earth is round Evidence: Best place – on a large body of water – large, flat, level surface Activity – watch a boat sail out over the horizon Experimental Results: Boat disappears sailing out – bottom first Boat reappears sailing in – top first Climbing to a higher vantage point brings the boat back into view. These results are consistent with a round earth. The hypothesis is proved.

MFMcGrawChap0-Scientific Method-Revised 5/5/107 Scientific Method Hypothesis  Experiment  Results A theory must explain currently known phenomena. A theory must make predictions that can be tested. Goals:  Theory as simple as possible  Few or no adjustable constants

MFMcGrawChap0-Scientific Method-Revised 5/5/108 As soon as a theory is established scientists start to investigate how far it can be stretched:  smaller dimensions,  larger dimensions,  larger and smaller masses. Theories are accepted as correct according to the currently available data but are also tested on new data as it becomes available Scientific Method

MFMcGrawChap0-Scientific Method-Revised 5/5/109 Disagreements with established theory sometimes arise  Initially attempt to modify the theory to fit in the new results  Try to add new concepts to theory Discoveries are not always that orderly but can benefit from luck, accidents and a prepared mind. X-Rays were discovered when leaks in shielding exposed some nearby photographic plates. Cosmic Background Radiation was discovered when trying to eliminate electrical noise in telephone transmission equipment. Scientific Method