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Watching/trying to understand this clip of Nadal is keeping me up:
Ok, so check out the frame 5 frames before contact. That is the bottom of Nadal's backswing/the start of his forward swing. The tip of the frame looks to be about a foot off the ground and about two feet behind the left foot. The racquet face is about 45 degrees to the court surface and the hitting elbow is either bent or straight (can't tell in this frame).
Moving into contact, watch how little shoulder rotation there is. The shoulders don't seem to be "turning into the shot" at all. Instead, the hitting arm is driving up and forward as a unit.
One frame before contact: check out the angle between the non-hitting racquet surface and Nadal's forehand--it looks to be 90 degrees if you're looking at his arm. But we cannot see the angle clearly by looking at Rafa's arm. Can we actually CLEARLY determine this angle? Hmm. Check out that shadow next to the bottom right hand corner of the viewing window (where it says Tennisplayer.net). What you see is that the angle is greater than 90 degrees--at the very least, I think it's a 100 degrees.
Contact: I guess actually a little after contact--the fact that you can't see the actual contact, even with a high speed camera, is indicative of Nadal's racquet speed. More on that later. The aforementioned angle is about a 100 degrees still and doesn't seem to have changed. Comparing this frame to the previous frame, one cannot say that there has been a discernible wrist release/snap--at least I don't think so. The elbow and hitting shoulder have also pushed forward. The angle of the racqueet face in the previous frame was perpendicular to the court. In this frame it's slightly closed (less than 90 degrees to the court). Though Nadal has an extreme grip, he's not hitting with an extremely closed racquet face, or a racquet face that is closed at all--it may very well have been perpendicular at contact or a degree or two closed. Contact is made a little higher than waist high and right in front of the right foot. Interestingly, the hitting arm is not straight--it's slightly bent.
The next 6 frames: Check out how that aforementioned angle hasn't changed. The wrist hasn't released. The point of maximum extension is the 6th frame from contact. The tip of the racquet looks to me to be about two feet past the front foot and I'm moderately estimating 6 feet off of the ground (based on Nadal's height of 6'1"--the tip is higher than his head but he's got a low foundation formed by being bent at the knees with his butt lowered). From contact, until the point of maximum extension, the racquet tip appears to have rotated 90 degrees.
Moving to the wrap: The tip will rotate 90 degrees more into a reverse finsish.
Ok, so let's estimate how far Rafa swung the tip of the racquet and use that to approximate his racquet speed. The tip vertically traveled from a foot off the ground at the bottom of the backswing to 6 feet off the ground at the point of maximum extension. That happened in the span of 11 frames on a 250 frame/sec video. So in about 11/250 or approximately 0.04 seconds Rafa's frame is approximated to have vertically travelled 5 feet. So in the vertical direction his racquet head speed is 5 ft/0.04 sec which equals 125 ft/s. To figure out how far the tip horizontally traveled, I looked at the frame that shows the bottom of the backswing. Then I looked at the frame that shows the point of maximum extension. Looking back at the frame that shows the bottom of the backswing, I approximated that Rafa's buttcap is diagonally located between these two points. Rafa's racquet is 27 inches long (Babolat Aero Pro Drive Standard model), so I think given these estimations, a reasonable approximation is that the racquet travelled 54 inches, 4 feet 6 inches, horizontally in 0.04 seconds which equals approximately 113 ft/s--although going by diagonals is not the best way to find horizontal displacement (like I said, these are approximations so a give here may be balanced out by a take there, and vice versa). Given the angle of this video, I was not able to determine the side-to-side movement in the racquet tip on Nadal's forehand and therefore do not have a velocity for this third dimension. But I'm going to continue with my approximations and hope you guys can correct me where I'm wrong.
Ok, so now we have two approximated velocities--horizontal (113 ft/s) and vertical (125 ft/s). What we need now is the vector sum of these two velocities to get the true, albeit approximated, racquet velocity that as I've stated, does not factor in side-to-side movement. Our vector sum comes out to be approximately 169 ft/s.
Translating that into miles/hour we end up discovering that Rafael Nadal may approximately have 115 miles/hour of racquet speed based on the distance that his racquet tip traveled in the vertical and horizontal directions (according to approximations based on visuals) from the point at which the racquest tip was at it's lowest point (during the bottom of the backswing/start of forward swing) to the point of maximum extension after contact, over the specified 11 frames (and given the 250 frame/second setting of the video clip), and ignoring (not being able to calculate for) side-to-side movement and velocity. Those were my methods of calculation--please correct me if I'm wrong in any way. Really, please do!
Assuming I'm somewhat right and that Rafael Nadal does generate 115 miles/hour of racquet head speed--well I don't know what to say about that, actually. His racquet head speed might actually be faster considering what I actually determined was the average velocity over the 11 frames and not the instantaneous velocity at contact. I'm simply amazed! Reportedly, Tiger Woods generates 120 miles/hour of club head speed (which is measured, I think, as instantaneous velocity at contact). But he's standing still. Rafael Nadal may be generating 115 miles/hour (or more) of racquet head speed on the dead run! Maybe that's an unfair comparison given that Tiger's driver weighs more than Rafa's Babolat? Whatever--they are two phenoms! Nike's pretty lucky, ey?
Looking at this clip and writing this forced me to re-evaluate the role of the wrist, the look of the bottom of the backswing/contact/point of maximum extension, and of course to brush up (after all, this is Nadal's topspin forehand) on some physics. I am taking the MCAT (Medical College Admissions Test) this August and will be done going over my physics after two more weeks! Hopefully my calculations, methods, and observations weren't that far off--otherwise I have a lot to review if I want to do well on the Physical Sciences portion of the exam and if I want to understand what's really going on in the world of professional tennis.
Let me know guys. Hope you found this interesting and enjoyable. I sure did.
Ok, so check out the frame 5 frames before contact. That is the bottom of Nadal's backswing/the start of his forward swing. The tip of the frame looks to be about a foot off the ground and about two feet behind the left foot. The racquet face is about 45 degrees to the court surface and the hitting elbow is either bent or straight (can't tell in this frame).
Moving into contact, watch how little shoulder rotation there is. The shoulders don't seem to be "turning into the shot" at all. Instead, the hitting arm is driving up and forward as a unit.
One frame before contact: check out the angle between the non-hitting racquet surface and Nadal's forehand--it looks to be 90 degrees if you're looking at his arm. But we cannot see the angle clearly by looking at Rafa's arm. Can we actually CLEARLY determine this angle? Hmm. Check out that shadow next to the bottom right hand corner of the viewing window (where it says Tennisplayer.net). What you see is that the angle is greater than 90 degrees--at the very least, I think it's a 100 degrees.
Contact: I guess actually a little after contact--the fact that you can't see the actual contact, even with a high speed camera, is indicative of Nadal's racquet speed. More on that later. The aforementioned angle is about a 100 degrees still and doesn't seem to have changed. Comparing this frame to the previous frame, one cannot say that there has been a discernible wrist release/snap--at least I don't think so. The elbow and hitting shoulder have also pushed forward. The angle of the racqueet face in the previous frame was perpendicular to the court. In this frame it's slightly closed (less than 90 degrees to the court). Though Nadal has an extreme grip, he's not hitting with an extremely closed racquet face, or a racquet face that is closed at all--it may very well have been perpendicular at contact or a degree or two closed. Contact is made a little higher than waist high and right in front of the right foot. Interestingly, the hitting arm is not straight--it's slightly bent.
The next 6 frames: Check out how that aforementioned angle hasn't changed. The wrist hasn't released. The point of maximum extension is the 6th frame from contact. The tip of the racquet looks to me to be about two feet past the front foot and I'm moderately estimating 6 feet off of the ground (based on Nadal's height of 6'1"--the tip is higher than his head but he's got a low foundation formed by being bent at the knees with his butt lowered). From contact, until the point of maximum extension, the racquet tip appears to have rotated 90 degrees.
Moving to the wrap: The tip will rotate 90 degrees more into a reverse finsish.
Ok, so let's estimate how far Rafa swung the tip of the racquet and use that to approximate his racquet speed. The tip vertically traveled from a foot off the ground at the bottom of the backswing to 6 feet off the ground at the point of maximum extension. That happened in the span of 11 frames on a 250 frame/sec video. So in about 11/250 or approximately 0.04 seconds Rafa's frame is approximated to have vertically travelled 5 feet. So in the vertical direction his racquet head speed is 5 ft/0.04 sec which equals 125 ft/s. To figure out how far the tip horizontally traveled, I looked at the frame that shows the bottom of the backswing. Then I looked at the frame that shows the point of maximum extension. Looking back at the frame that shows the bottom of the backswing, I approximated that Rafa's buttcap is diagonally located between these two points. Rafa's racquet is 27 inches long (Babolat Aero Pro Drive Standard model), so I think given these estimations, a reasonable approximation is that the racquet travelled 54 inches, 4 feet 6 inches, horizontally in 0.04 seconds which equals approximately 113 ft/s--although going by diagonals is not the best way to find horizontal displacement (like I said, these are approximations so a give here may be balanced out by a take there, and vice versa). Given the angle of this video, I was not able to determine the side-to-side movement in the racquet tip on Nadal's forehand and therefore do not have a velocity for this third dimension. But I'm going to continue with my approximations and hope you guys can correct me where I'm wrong.
Ok, so now we have two approximated velocities--horizontal (113 ft/s) and vertical (125 ft/s). What we need now is the vector sum of these two velocities to get the true, albeit approximated, racquet velocity that as I've stated, does not factor in side-to-side movement. Our vector sum comes out to be approximately 169 ft/s.
Translating that into miles/hour we end up discovering that Rafael Nadal may approximately have 115 miles/hour of racquet speed based on the distance that his racquet tip traveled in the vertical and horizontal directions (according to approximations based on visuals) from the point at which the racquest tip was at it's lowest point (during the bottom of the backswing/start of forward swing) to the point of maximum extension after contact, over the specified 11 frames (and given the 250 frame/second setting of the video clip), and ignoring (not being able to calculate for) side-to-side movement and velocity. Those were my methods of calculation--please correct me if I'm wrong in any way. Really, please do!
Assuming I'm somewhat right and that Rafael Nadal does generate 115 miles/hour of racquet head speed--well I don't know what to say about that, actually. His racquet head speed might actually be faster considering what I actually determined was the average velocity over the 11 frames and not the instantaneous velocity at contact. I'm simply amazed! Reportedly, Tiger Woods generates 120 miles/hour of club head speed (which is measured, I think, as instantaneous velocity at contact). But he's standing still. Rafael Nadal may be generating 115 miles/hour (or more) of racquet head speed on the dead run! Maybe that's an unfair comparison given that Tiger's driver weighs more than Rafa's Babolat? Whatever--they are two phenoms! Nike's pretty lucky, ey?
Looking at this clip and writing this forced me to re-evaluate the role of the wrist, the look of the bottom of the backswing/contact/point of maximum extension, and of course to brush up (after all, this is Nadal's topspin forehand) on some physics. I am taking the MCAT (Medical College Admissions Test) this August and will be done going over my physics after two more weeks! Hopefully my calculations, methods, and observations weren't that far off--otherwise I have a lot to review if I want to do well on the Physical Sciences portion of the exam and if I want to understand what's really going on in the world of professional tennis.
Let me know guys. Hope you found this interesting and enjoyable. I sure did.
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