Accuracy of hourglass Sand Timers Study the accuracy of sand timers
Introduction: Hourglasses are among a number of ingenious timekeeping devices used before the development of clocks in the Middle Ages. Hourglasses, also called sandglasses, sand timers, sand clocks, or egg timers, are a relatively recent invention. There are many factors that contribute
to the ability of an hourglass to accurately measure time. The type and
quality of sand is key. It must have a rate of flow that does not
fluctuate. Sand that is too coarse will wear away the glass, eventually
making the neck too large. Most important is the ratio of the neck (the
hole, or tube) width to the diameter of the sand particles.
We still use the hourglass to keep track of time. Just think of its many uses for cooking and for playing games! Question, Purpose or objective of the project: Are sand timers accurate? The purpose of this project is to study the accuracy of sand timers by comparing them with each other and a modern clock. Materials: You will need the following materials for your experiment.
Project Variables:
Procedure:
Actual cycle times of 10 identical hourglasses:
After you complete your three trials, calculate the average cycle time for each counter. To do that add the times you entered for the three trials of each hourglass and divide the sum by three. Enter the averages in the last row of your data table. Draw a graph: You may make a bar graph to visually present your results. Bar graphs are easy to understand and are appropriate for data that are not directly related to each other. To construct your bar graph, use one vertical bar for each hourglass you test. Number the bars from 1 to 10 to correspond to the number of hourglasses you have tested. The height of each bar represents the average cycle time for the corresponding hourglass. For example you may draw a vertical line that is 189 millimeters to show a timing cycle of 189 seconds (that is equivalent to three minutes and 9 seconds.) Draw a conclusion: In your conclusion write if the sand timers are accurate. Describe what are the problems with sand timers and why they are not as accurate of mechanical and electronic timers and clocks. References: http://www.tkyoung.com/history.html http://www.loc.gov/rr/scitech/mysteries/hourglass.html http://www.dencities.com/denmall/denmallunique8a.html
