Direct and Indirect Measurements

A metric ruler was used to measure the thickness of three different beans. The results are listed below.

Bean 1 - 0.5cm
Bean 2 - 0.47cm
Bean 3 - 0.39cm
Average - 0.45cm

Another way to measure the thickness of the beans is by using the volume of a cylinder method. The volume of 10 beans were taken using water in a graduated cylinder. The beans were then laid out on a table in a circle and the diameter taken. This was repeated 3 times with 10 different beans every time. The thickness of each bean was determined with the following equation: V=pi x r(squared) x h, in which the height of the beans equaled the volume of the beans divided by pi times the radius of the circle squared. The information is listed below.

Trial 1 - Vol = 40mL, Radius = 5.0cm, Height = 0.51cm
Trail 2 - Vol = 41mL, Radius = 5.2cm, Height = 0.48cm
Trail 3 - Vol = 38mL, Radius = 4.9cm, Height = 0.50cm
Average - Vol = 40mL, Radius = 5.0cm, Height = 0.51cm

1. Which measurement is a direct measurement?
2. Which measurement is an indirect measurement?
3. Which measurement gives the more accurate measurement of the thickness of the bean?
4. What are some sources of error in making the indirect measurement? How might they be reduced?
5. When might indirect measurements be useful?

This assignment is due on Monday, September 10th by midnight.

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