Arrow Through An Apple
         Movie Clip

 
(NOTE: This is an MPG movie... you may need to get the Quicktime PlugIn.

Also, it is an unedited video clip... please ignore sections other that for the flying arrows.)

As the arrow passes through the apple, it shares only a small amount of its momentum. Play the quicktime movie several more times using the arrow on the bottom left of the frame. You may wish to increase the volume... click and hold onto the speaker button.

Let's gather data to determine the approximate speed of the arrow...

Standard arrows are between 24" and 31" in length. Assume this one is 26.5" long. If 1 inch = 2.54 cm,

1. What is the length of the arrow in centimetres?

This quicktime movie plays the first segment with the gren apple is 19 s long while 192 frames were playing. This works out to 0.099 s or roughly 0.10 s per frame. This means the playback is at 10 frames per second.

However, this whole sequence was filmed with a special high speed camera that takes shots at 200 times the normal speed, so effectively this is 2000 frames per second.

2. What is the real time per frame, or time per click of the forward arrow?

Use the stop-motion / frame advance button on the bottom right of the frame to click throught the movie frame by frame and observe the collision of the first sequence very carefully. Notice the point that you first see the tip of the arrow and count the number of frames that you have to advance before you first see the very end of the arrow.

3. Using the count of frames from above, determine the time it takes for the arrow to fully appear.

4. Can you calculate the approximate speed of the arrow using the above information above as a scale?

5. If you know that the viewing window's width represents 50 cm, then explain how you can calculate the speed of the arrow in another way.

6. Explain how you could determine the speed of the apple.

For a technical discussion on the arrow speed and the strength of bows, please visit the Primitive Archer Magazine site. Within this article, you should be able to find enough information to determine if your estimate of the speed of the arrow is reasonable.

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