Biology Experiment Essay

2035 Words Jun 20th, 2014 9 Pages
11a, lab 1: Motion, Measurement and Statistics

In the first lab we will investigate the motion of a ball rolling down an inclined plane. We will use this simple system to investigate the concept of systematic and random measurement uncertainties to understand how much we can trust a measurement. We will then compare the experimental outcome with theory.

I. Ball on an inclined plane: Measuring motion

We want to measure the motion of a ball that rolls down on an inclined plane and see whether this matches what we would expect. We will roll a ball down a tilted aluminum plate where gravity will accelerate the ball. It then rolls along a level surface (Plexiglas) where it should roll with approximately constant velocity as
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Velocity is the length the ball travels per time.

1. Can you think of two different ways to measure the velocity? Hint: You can use a ruler to measure/define length, and a metronome/clock to measure/define a time interval. Describe the two alternative methods. (Use headphones for the metronome on the computer – otherwise your fellow students might get annoyed… ().

2. How do you decide what length or time interval you use to get the best possible precision? In other words, why might your precision be negatively affected if your length/time is either (a) too short or (b) too long?

3. Try both methods, and discuss them with your TF. Decide which one you will use for the following experiment. Also, look around what others are using and make sure not everyone is using the same method. This way we can later compare the statistical error of both methods.

4. Can you think of a way to measure the velocity without a time keeping instrument (stopwatch/ruler), just with a ruler? There is actually an easy way … can you figure it out? Discuss it with your TF! (If you have time left at the end, try it out for a bonus!)


• We now have a measurement technique in place that we will use to measure velocity. Before you take a dataset, prepare a worksheet with the logger pro software that allows you to input your

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