Experiment 3 The Stopwatch In this experiment you will investigate error and uncertainty involved with using a stopwatch Materials 1 Marble Stopwatch Constant Drop Height Ex Table Top or Door Frame You Must Provide Procedure 1 Choose a place or object like a table top or top of a door from which you can constantly drop a marble at the same height Note Choosing an object that has a higher drop distance will be easier to time than shorter drop distances 2 Read the directions that come with your stopwatch to become familiar with how to use and access the stopwatch mode 3 Hold the marble at the designated drop height in one hand and the stopwatch in the other hand If necessary a willing participant can help with timing or dropping the marble 4 Drop the marble from the designated drop height and start the stopwatch at the same time 5 Stop the stopwatch at the same time the marble hits the floor Record the time in Table 3 6 Repeat Steps 3 4 four more times for a total of five trials Table 3 Time Data for Dropped Marble 2014 eScience Labs LLC All Rights Reserved Drop Trial Time s 1 0 57 second 2 0 45 seconds 3 0 33 seconds 4 0 47seconds 5 0 38 seconds Post Lab Questions 1 What are the advantages and disadvantages of using a stopwatch to measure time A stopwatch is pretty unreliable given it is based off human reaction time 2 What are sources of uncertainty when using a stopwatch sound of the marble hitting the floor and the instant the marble hit the floor can be two separate times The amount of time it takes the human brain to process the marble hitting the floor or the sound of the marble hitting the floor then to press the stop button leads to a large source of error Table 3 demonstrates the wide range of times recorded for a marble to hit the ground from the same height Although these results should be very close together they are not This leads to the conclusion that there is a large source of uncertainty using a stopwatch 2014 eScience Labs LLC All Rights Reserved
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