Measure Rev Rate
Calculating Rev Rate requires a video.
Place Tape from PAP to above fingers.
- Make sure the tape is contrasting in color to the ball. This will allow you to easily see the rotations.
Film a few throws
TAKE NOTE of the Frames Per Second you're recording in. Most video cameras are either NTSC-30FPS or PAL-25FPS, but other rates do exist.
On a frame-by-frame player (Quicktime) count the number of times the tape revolves over 10 frames. Be as exact as possible with this calculation.
- 1/4 rotation over 10 frames is equivalent to 45 RPM, so a minor mistake in reading the video can be large
- To minimize error, throw more than one shot, and average your results.
- The higher the video quality, and the higher the frame rate, the more exact results you can obtain.
A short duration such as 10 frames is best, as this allows you to remove many effects of the lane such as friction.
You will end up with
X Revolutions / 10 Frames
At this point, it's simply conversion factors from high school science class:
- I am using 30FPS, as most video cameras in the US will use this *
(x Revs / 10 frames} x (30 Frames / Second) = (revs / Second)
(Revs / Second) (60 Seconds / 1 Minute)
Multiply X Revs by 3, (or multiply by 30 and divide by 10)
The Multiply your result by 60. It's pretty simple!
For example:
If the ball Completes 2 FULL rotations only over 10 frames
2/10 * 30/1 * 60/1 = 360RPM
Video
Video Courtesy of JustinWi
