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class="jsx-4069620119">The Mystery and Physics of the Spiral Football Pass</h1><div class="jsx-4069620119 intro"><p>There are two key players involved: gravity and angular momentum.</p></div><div class="jsx-4069620119 meta"><span class="jsx-4069620119"><b class="jsx-4069620119">Publish Date:</b> <time dateTime="2023-02-15" class="jsx-4069620119">2/15/23</time></span><span class="jsx-4069620119">Topic: <a class="jsx-4069620119 topic" href="/wgbh/nova/topic/physics/"> Physics + Math</a></span><span id="topic_pageview" class="jsx-4069620119 assistive-text">Physics & Math</span><span id="brand_pageview" class="jsx-4069620119 assistive-text">NOVA</span><div class="jsx-4069620119"><div class="jsx-2313856539"><span class="jsx-2313856539 label">Share</span><ul class="jsx-2313856539"><li class="jsx-2313856539"><a href="https://twitter.com/share?url=https://www.pbs.org/wgbh/nova/video/mystery-and-physics-of-spiral-football-pass/" target="_blank" rel="noreferrer" class="jsx-2313856539"><svg 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M57.1,58.5c-4,3.7-10.2,3.7-14.3,0l-5.4-5.2L16.1,73.6 c1.5,1.9,3.7,2.9,6.1,2.9h55.4c2.4,0,4.6-1.1,6.1-2.9L62.5,53.3L57.1,58.5z" class="jsx-2313856539"></path></svg></a></li></ul></div></div></div></header></div></div><div class="jsx-3298f89b5786ce6a content"><div class="jsx-3298f89b5786ce6a episode-content"><div class="jsx-3298f89b5786ce6a block-content"><div class="jsx-3298f89b5786ce6a producers"><span class="jsx-3298f89b5786ce6a">By Ana Aceves</span></div><div class="jsx-3298f89b5786ce6a"><p>The way the spiral football pass travels through the air baffled physicists for years.</p></div><div role="presentation" class="jsx-7809646997e91c88 accordions"><div role="tab" class="jsx-7809646997e91c88"><h3 aria-level="3" class="jsx-7809646997e91c88"><button id="label-transcript-0" aria-controls="transcript-0" aria-expanded="false" class="jsx-7809646997e91c88 ">Transcript</button></h3></div><div role="tab" class="jsx-7809646997e91c88"><h3 aria-level="3" class="jsx-7809646997e91c88"><button 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are two key players involved: gravity and angular momentum.","transcript":"\u003cp\u003e\u003cb\u003eThe Mystery and Physics of the Spiral Football Pass\u003cbr/\u003e\u003c/b\u003ePublished February 15, 2023\u003cbr/\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e The perfect football pass, a thing of beauty—and bewilderment. The way the football travels mid-air baffled physicists for years.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSteve Lamoreaux\u003c/b\u003e: If you're in the physicist's world, you expect a football to travel like this and come down. When you watch a long pass from a talented quarterback, you can see that the football does travel like that.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e So why does the nose of the football go from pointing upward to rotating downard when most things stay the same orientation as they move through the air? There are two key players involved: gravity and angular momentum. Ok, so what is angular momentum? First, it’ll help to understand momentum. You’re probably used to experiencing \u003ci\u003elinear\u003c/i\u003e momentum. Imagine you’re a passenger in a car traveling at 40 miles per hour and the driver suddenly breaks, but you continue moving forward. That’s what seatbelts are for.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSteve Lamoreaux:\u003c/b\u003e A body in motion tends to stay in motion unless acted on by a force, and that's conservation of momentum.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Then there is angular momentum, which is when an object with mass is spinning. You can see this property in action when an ice skater speeds up when they pull their arms in. In football, conservation of angular momentum is the reason why the ball changes orientation while it spins through the air. Let's compare a football spinning vertically on a flat surface to a spinning top.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTim Gay:\u003c/b\u003e The top of the top will describe a circular orbit around a vertical axis. The vertical axis is set up by the force of gravity. Gravity is trying to pull the top over, but the top refuses to fall over. To conserve angular momentum, it processes in a circle.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e A football acts kind of like a top—a symmetrical top.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTim Gay:\u003c/b\u003e Now, the axis about which the ball rotates is not caused by gravity. In the case of the football, it's precessing around the onrushing force of air that the ball experiences.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e The force of the air pushes on the ball, causing it to wobble around its spinning axis, and this wobble eventually pushes the nose down.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTim Gay:\u003c/b\u003e Gravity absolutely acts on the football, but its effect is to cause the ball to go up and then come down in that curved parabolic trajectory.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Put them all together and you get that beautiful pass. But to gain the most amount of yards in the shortest amount of time, the quarterback needs to keep a lot of things in mind.\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e The thing I look for in a quarterback is a lot of intelligence and understanding. After that it's accuracy with the arm, timing to get the ball out, and just awareness.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e And the spin of the ball is crucial to getting it go the distance.\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e If you don't throw a spiral, that thing is going to flutter. We call those ducks. The ball starts to flutter, doesn't get velocity, doesn't get distance and those end up getting intercepted by the defenders.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Here’s how they get that perfect spiral.\u003c/p\u003e\u003cp\u003e\u003cb\u003eBernard Davis:\u003c/b\u003e So your firm grip must come from these fingers. And the other last two in the back is also for guidance. And also try to have like a gap right here.\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e From that, it's all about where your arm is going and then the snap of your wrist.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e And they have to release the ball quickly. In those seconds…\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e So once the ball is snapped, you know, the quarterback is focused on several different things. So we're catching the ball, we're also scanning what's going on in front of us. As we do that, we're backing up away from the line where we're going to throw the ball. So as we're doing that, we're actually flipping the ball to put the laces on our hand.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Physics may be an integral part of football, but to players…\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e It's all about timing and practice and repetition.\u003cbr/\u003e\u003c/p\u003e","credits":"\u003cp\u003e\u003cb\u003ePRODUCTION CREDITS\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDigital Producer: Ana Aceves\u003c/p\u003e\u003cp\u003eNarration: Emily Zendt\u003c/p\u003e\u003cp\u003eProduction Assistance: Abe Musselman\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSpecial Thanks: Boston Bandits\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eMEDIA CREDITS\u003c/b\u003e\u003c/p\u003e\u003cp\u003eArchival:\u003c/p\u003e\u003cp\u003eInternet Archive\u003c/p\u003e\u003cp\u003ehans draiman / The Noun Project / CC-BY\u003c/p\u003e\u003cp\u003eGan Khoon Lay / The Noun Project / 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are two key players involved: gravity and angular momentum.","transcript":"\u003cp\u003e\u003cb\u003eThe Mystery and Physics of the Spiral Football Pass\u003cbr/\u003e\u003c/b\u003ePublished February 15, 2023\u003cbr/\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e The perfect football pass, a thing of beauty—and bewilderment. The way the football travels mid-air baffled physicists for years.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSteve Lamoreaux\u003c/b\u003e: If you're in the physicist's world, you expect a football to travel like this and come down. When you watch a long pass from a talented quarterback, you can see that the football does travel like that.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e So why does the nose of the football go from pointing upward to rotating downard when most things stay the same orientation as they move through the air? There are two key players involved: gravity and angular momentum. Ok, so what is angular momentum? First, it’ll help to understand momentum. You’re probably used to experiencing \u003ci\u003elinear\u003c/i\u003e momentum. Imagine you’re a passenger in a car traveling at 40 miles per hour and the driver suddenly breaks, but you continue moving forward. That’s what seatbelts are for.\u003c/p\u003e\u003cp\u003e\u003cb\u003eSteve Lamoreaux:\u003c/b\u003e A body in motion tends to stay in motion unless acted on by a force, and that's conservation of momentum.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Then there is angular momentum, which is when an object with mass is spinning. You can see this property in action when an ice skater speeds up when they pull their arms in. In football, conservation of angular momentum is the reason why the ball changes orientation while it spins through the air. Let's compare a football spinning vertically on a flat surface to a spinning top.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTim Gay:\u003c/b\u003e The top of the top will describe a circular orbit around a vertical axis. The vertical axis is set up by the force of gravity. Gravity is trying to pull the top over, but the top refuses to fall over. To conserve angular momentum, it processes in a circle.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e A football acts kind of like a top—a symmetrical top.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTim Gay:\u003c/b\u003e Now, the axis about which the ball rotates is not caused by gravity. In the case of the football, it's precessing around the onrushing force of air that the ball experiences.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e The force of the air pushes on the ball, causing it to wobble around its spinning axis, and this wobble eventually pushes the nose down.\u003c/p\u003e\u003cp\u003e\u003cb\u003eTim Gay:\u003c/b\u003e Gravity absolutely acts on the football, but its effect is to cause the ball to go up and then come down in that curved parabolic trajectory.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Put them all together and you get that beautiful pass. But to gain the most amount of yards in the shortest amount of time, the quarterback needs to keep a lot of things in mind.\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e The thing I look for in a quarterback is a lot of intelligence and understanding. After that it's accuracy with the arm, timing to get the ball out, and just awareness.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e And the spin of the ball is crucial to getting it go the distance.\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e If you don't throw a spiral, that thing is going to flutter. We call those ducks. The ball starts to flutter, doesn't get velocity, doesn't get distance and those end up getting intercepted by the defenders.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Here’s how they get that perfect spiral.\u003c/p\u003e\u003cp\u003e\u003cb\u003eBernard Davis:\u003c/b\u003e So your firm grip must come from these fingers. And the other last two in the back is also for guidance. And also try to have like a gap right here.\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e From that, it's all about where your arm is going and then the snap of your wrist.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e And they have to release the ball quickly. In those seconds…\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e So once the ball is snapped, you know, the quarterback is focused on several different things. So we're catching the ball, we're also scanning what's going on in front of us. As we do that, we're backing up away from the line where we're going to throw the ball. So as we're doing that, we're actually flipping the ball to put the laces on our hand.\u003c/p\u003e\u003cp\u003e\u003cb\u003eNarrator:\u003c/b\u003e Physics may be an integral part of football, but to players…\u003c/p\u003e\u003cp\u003e\u003cb\u003eShane Cheltenham:\u003c/b\u003e It's all about timing and practice and repetition.\u003cbr/\u003e\u003c/p\u003e","credits":"\u003cp\u003e\u003cb\u003ePRODUCTION CREDITS\u003c/b\u003e\u003c/p\u003e\u003cp\u003eDigital Producer: Ana Aceves\u003c/p\u003e\u003cp\u003eNarration: Emily Zendt\u003c/p\u003e\u003cp\u003eProduction Assistance: Abe Musselman\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eSpecial Thanks: Boston Bandits\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eMEDIA CREDITS\u003c/b\u003e\u003c/p\u003e\u003cp\u003eArchival:\u003c/p\u003e\u003cp\u003eInternet Archive\u003c/p\u003e\u003cp\u003ehans draiman / The Noun Project / CC-BY\u003c/p\u003e\u003cp\u003eGan Khoon Lay / The Noun Project / CC-BY\u003c/p\u003e\u003cp\u003eShutterstock\u003c/p\u003e\u003cp\u003eStoryblocks\u003c/p\u003e\u003cp\u003eMusic: APM\u003c/p\u003e\u003cp\u003e© WGBH Educational Foundation 2023\u003c/p\u003e","resources":"","editors_note":"","participants":[],"newsletter_modal_enabled":true,"producers":[{"first_name":"Ana","middle_name":"","last_name":"Aceves","slug":"anaaceves","gender":null,"birth_date":null,"short_biography":"","long_biography":"","website":"","twitter_handle":"","mugshot":null,"mugshot_credit":"","meta_description":"","affiliation":[]}]},"popular_content":{"popular_content":[{"content_type":"episodepage","topic":"earth","brand":"nova","length":3210,"title":"Arctic Sinkholes","slug":"arctic-sinkholes","part_of_a_series":false,"hero_image":{"mime_type":"image/jpeg","alt_text":"","src":"https://www.pbs.org/wgbh/nova/media/original_images/arctic-sinkholes-img.jpg","renditions":[{"width":300,"height":168,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-300.jpg","contentType":"application/vnd.theseus+scaled_image"},{"width":400,"height":225,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-400.jpg","contentType":"application/vnd.theseus+scaled_image"},{"width":600,"height":337,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-600.jpg","contentType":"application/vnd.theseus+scaled_image"},{"width":800,"height":450,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-800.jpg","contentType":"application/vnd.theseus+scaled_image"},{"width":1500,"height":843,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-1500.jpg","contentType":"application/vnd.theseus+scaled_image"},{"width":1920,"height":1080,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-2000.jpg","contentType":"application/vnd.theseus+scaled_image"},{"width":1920,"height":1080,"src":"https://www.pbs.org/wgbh/nova/media/images/arctic-sinkholes-img.width-2500.jpg","contentType":"application/vnd.theseus+scaled_image"}],"contentType":"application/vnd.theseus+image"},"intro":null,"short_description":"\u003cp\u003eIn the Arctic, enormous releases of methane, a potent greenhouse gas, threaten the climate.\u003c/p\u003e","long_description":"\u003cp\u003eColossal explosions shake a remote corner of the Siberian tundra, leaving behind massive craters. 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