Why Does the Hammer Appear to Change Rotation Direction in Mid-Air?

[Timoothy]

Hammer Rotation Mystery.?

Hi...
Below is a link that shows a blond Russian lady Hammer thrower (ther are about 4 other people befor the video gets to the blond Russian lady) which includes slow motion video of when her hammer hits the ground.!



in the video of the Russian lady... when she released the hammer... an observer up in the stands woud have seen the hammer rotatin CCW... but the slow motion part of the video (which is shown after her throw) shows that the hammer is rotatiin CW jus befor it hits the ground... what causes the CCW release of the hammer to change to a CW rotaton befor it hits the ground.?

 

[xboy]

That's an interesting question. I wonder why no one has attempted an answer already. Perhaps the hammer has undergone a 180 degree rotation about an axis perpendicular to both the length and the axis along which it is rotated? In other words, the near end is now the far end?

 

[Timoothy]

That's an interesting question. I wonder why no one has attempted an answer already. Perhaps the hammer has undergone a 180 degree rotation about an axis perpendicular to both the length and the axis along which it is rotated? In other words, the near end is now the far end?

That souns simular to what I've suspected... that not only does the hammer rotate CCW (10 to 12 times) over the length of its flight... it has also done a 180 degree "spiral" (the top of the hammer (ball) at release is now on the bottom when it lands)... which woud make the hammer apear to have changed its directon of rotaton to CW at the end of its flight.!

About 8 other people have answrd in other groops but so far me an you are the onliy ones to suggest the additional 180 degree rotaton about a perpendicular axis.!

 

[rcgldr]

Optical illusion. As far as I can tell, the axis of rotation has changed little since the time of release. I used hypercam to capture the video and watch it in slow motion. Towards the end, the ring passes "behind" the ball, the hammer, chain, and ring are still rotating CCW at the end of the video. I made a 1/10th speed video of the sequence in question, but it's not that clear:

http://jeffareid.net/misc/hmrthrw.wmv

 

[Timoothy]

Optical illusion. As far as I can tell, the axis of rotation has changed little since the time of release.

Towards the end, the ring passes "behind" the ball, the hammer, chain, and ring are still rotating CCW at the end of the video.

Hi Jeff... i appreciate you'r input also... wit som discusson this issue jus mite get figered out in my mind.!
An jus to be clear... my positon is not set in stone... i want to know what's really goin on wit the hammer.!

oK... to quickly identify our diference in percepton of directon of rotaton... near the end of the slow moton video i see the handle (ring) pass in front of the ball in a CW rotaton.!

Say the ball is the center of a clock (which is facin up)... the slow moton part of the video begins wit the handle (ring) in the 10:00 positon (left of the ball)... then moves CW to 11:00 to 12:00 to 1:00 to 2:00 to 3:00 to 4:00... an at the 4:00 positon the chane apears to becom shorter an even shorter at the 5:00 positon... an at the 6:00 positon the handle is in front of the ball pontin nearly directly at the camera so the length of the chane apears to be near zero... then the handle continues to rotate CW to the 7:00 positon to 8:00 to 9:00 to 10:00 which is about when the hammer hits the ground.!

The thang I am sure about is that the hammer is rotatin CCW when released... an it can't reverse its directon of rotaton durin its flight down the field... so i want the hammer to be rotatin CCW in the slow moton part of the video but to me the directon of rotaton apears to be CW.

I can't view the U-Tube video wit the internet divice I am usin... but the nest time i have access to a computer i will look at the slow moton part of the video wit a open mind to CCW rotaton.!

 

[rcgldr]

Optical illusion. As far as I can tell, the axis of rotation has changed little since the time of release. The hammer, chain, and ring are still rotating CCW at the end of the video.

Say the ball is the center of a clock (which is facin up)... the slow moton part of the video begins wit the handle (ring) in the 10:00 positon (left of the ball), but the handle is apparently closer to the camera than the ball. The illusion is that the handle is further away than the ball.

As I mentioned previously I doubt the axis of rotation has changed very much. The axis is tilted away from the camera so that the handle is higher when closer than the ball to the camera, and lower when it's further away from the camera while rotating CCW as viewed from above. In my opinion, this never changes.

 

[Timoothy]

As I mentioned previously I doubt the axis of rotation has changed very much. The axis is tilted away from the camera so that the handle is higher when closer than the ball to the camera, and lower when it's further away from the camera while rotating CCW as viewed from above. In my opinion, this never changes.

After readin you'r earlier reply i went bak to a diferent groop an read the answr a guy named Janus gave (link below):::

http://www.sciforums.com/showpost.php?p=2162675&postcount=9


He describes in mor detale what you'r talkin about... an now id bet a small amount of money its the corect answr:-)
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[An Edit below]
I looked at the slow-moton part of the video on a computer today tryin to see the hammer rotatin CCW... an on about the 4th try thar it was... a perfect CCW rotaton... so now the mystery is solved in my mind... the hammer is rotatin CCW as it lands (jus as it woud be espected to)... an that it can apear to be rotatiin CW is an illusion jus like Janus said.!

Below is a rotatin-lady illusion like Janus was referrin to:::

http://www.news.com.au/common/imagedata/0,,5693171,00.gif

Last edited by cluelusshusbund;