May 20th, 2010

Brielle Spencer

High Speed Video Analysis of the Force by a Bowstring on an Arrow

Bows and arrows have been used for years for both hunting and recreational purposes, and over time innovations have been made to the bow to make it easier for the user. An arrow needs to have high force on it in order to accelerate to high speed, but the user must also be capable of drawing back and easily holding the string in this position. The purpose of this project was to analyze the force by a bowstring on a Mathews Solocam Bow on an arrow as it is shot. Using high-speed video analysis, the net force on the arrow was measured, and a force versus distance graph was analyzed to determine how the force varies as a function of distance while the arrow is in contact with the string. The data showed three distinct regions: (1) an initially rapid increase in the force (just after the arrow is released), (2) a nearly uniform, linear increase, and (3) a nearly constant force that acts for more than half the distance traveled before the arrow leaves the bow. This is consistent with the design of the bow that when drawn is initially difficult to pull, becomes easier to pull, and then becomes very easy to hold when fully drawn.

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