STEM FAIR PROJECT Pendulum Problem Miss Daskivich’s 3 rd Grade Class - Northview Elementary

STATEMENT OF THE PROBLEM Does the length of the string determine the number of swings in a given time?

PROJECT OVERVIEW Students will test different string lengths of 25 cm., 50 cm, and 75 cm.

RESEARCH – 1 st point -The pendulum has been used since the 16 th century to measure time. – 2 nd point- Galileo Galilei was the first European to really study pendulums and he discovered that their regularity could be used for keeping time, leading to the first clocks. Galileo Galilei – 3 rd point-The slowing down and stopping is due to the forces of friction and gravity. – 4 th point- In 1656, the Dutch inventor and mathematician, Huygens, was the first man to successfully build an accurate clock. – 5 th point- If you pull back a pendulum and then let it go, the time it takes to swing over and then return back to its starting position is one period.

VARIABLES Controlled variables: Type of string, size and weight of the washers, time for each trial, and swing height. Independent variable: The length of the string. Dependent variable: The measure of the number of swings in a one minute period.

HYPOTHESIS Based on the research, we would expect that if we changed the length of the string, this will change the number of swings in one minute. When we lengthen the string it will take longer to go back and forth and decrease the number of swings in one minute.

MATERIALS Cotton kite string. Metal washers (One per group) Yard stick to mark the string. Marker to mark the string. Stop watch to time one minute or clock with second hand.

PROCEDURE 1 – Students will tie their washer to one end of the string. 2 - Students will mark their string by laying it along side a meter stick. The end with the washer will be even with zero. 3 - With the marker they will mark the string at 25cm, 50cm, and 75cm. 4 - One student will hold the string steady in the air at 25cm, another will hold the washer horizontally and release it when another student says go. The fourth student will time for one minute and another will count the number of period swings in one minute and record it in the chart for the group. Repeat for three trials. 5 – Repeat step four for lengths 50cm and 75cm.

SCIENTISTS IN ACTION!

DATA/OBSERVATIONS Length of the String Number of Swings Trial 1 (Group Averages) Number of Swings Trial 2 (Group Averages) Number of Swings Trial 3 (Group Averages) Average Number of Swings (Group Averages) 25 cm cm cm

CONCLUSION We can conclude from our data that our hypothesis was correct. The number of swings was affected by the length of the string. The longer the string, the longer it took for the pendulum to swing one period, thus the longer the string the less swings recorded in one period. We found that the number of swings decreased by about 5 swings when the length of the string increased by 25 centimeters. Further exploration: We wondered about other experiments that we could do with a pendulum. We could test whether different weights would have an affect on the number of swings, swings through different mediums or the arc of the swing would have different results.

WORKS CITED Electronic Sites: 7_SS.pdf 7_SS.pdf