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Rifles, Reloading, Optics, Equipment
Rifles, Bullets, Barrels & Ballistics
Question on Applied Ballistics App and Coriolis
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<blockquote data-quote="Pdvdh" data-source="post: 1188468" data-attributes="member: 4191"><p>Watching the globe rotate on the north/south poles axis, the reason the vertical component of coriolis drift is largest at the equator, and null and void at the poles, also become obvious - in a manner not likely to be forgotten anytime soon. </p><p></p><p>The equator is the farthest radius from the north/south axis. When the earth spins on that axis, the surface of the earth is rotating at the highest rate of speed at the equator - where the earth's surface is the farthest from the axis of rotation. Which means your target/game animal travels a greater distance between the time the bullet leaves the muzzle, and the bullet strikes the target/game animal.</p><p></p><p>It'll now be much easier for me to remember the primary affecting aspects of both both components of coriolis. If I find myself fuzzy over horizontal and vertical coriolis in the future, I'll just remember the rotating globe. </p><p></p><p>The eotvos component of vertical coriolis is pretty minor - not worth researching, unless you're a real nerd/geek. <img src="data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7" class="smilie smilie--sprite smilie--sprite1" alt=":)" title="Smile :)" loading="lazy" data-shortname=":)" /> For all you nerds/geeks, it should be easy to follow this explanation from Wikipedia!</p><p></p><p>"<strong><em><span style="font-family: 'Comic Sans MS'">The Eötvös effect is the change in perceived gravitational force caused by the change in centrifugal acceleration resulting from eastbound or westbound velocity. When moving eastbound, the object's angular velocity is increased (in addition to the earth's rotation), and thus the centrifugal force also increases, causing a perceived reduction in gravitational force.</span></em></strong></p><p><strong><em><span style="font-family: 'Comic Sans MS'"></span></em></strong><em><span style="font-family: 'Comic Sans MS'"></span></em></p><p><em><span style="font-family: 'Comic Sans MS'">In the early 1900s (decade), a German team from the Institute of Geodesy in Potsdam carried out gravity measurements on moving ships in the Atlantic, Indian and Pacific Oceans. While studying their results the Hungarian nobleman and physicist Baron Roland von Eötvös (see Loránd Eötvös) (1848–1919) noticed that the readings were lower when the boat moved eastwards, higher when it moved westward. He identified this as primarily a consequence of the rotation of the earth. In 1908 new measurements were made in the Black Sea on two ships, one moving eastward and one westward. The results substantiated Eötvös' claim. Since then geodesists use the following formula to correct for velocity relative to the Earth during a measurement run.</span></em><span style="font-family: 'Comic Sans MS'"></span></p><p><span style="font-family: 'Comic Sans MS'"></span></p><p><span style="font-family: 'Comic Sans MS'"> a_r = 2 \Omega u \cos \phi + \frac{u^2 + v^2}{R}. </span></p><p><span style="font-family: 'Comic Sans MS'"></span></p><p><span style="font-family: 'Comic Sans MS'"><em>Here,</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em></em></span></p><p><span style="font-family: 'Comic Sans MS'"><em> a_r is the relative acceleration</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em> \Omega is the rotation rate of the Earth</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em> u is the velocity in latitudinal direction (east-west)</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em> \phi is the latitude where the measurements are taken.</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em> v is the velocity in longitudinal direction (north-south)</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em> R is the radius of the Earth</em></span></p><p><span style="font-family: 'Comic Sans MS'"><em></em></span></p><p><span style="font-family: 'Comic Sans MS'"><em>The first term in the formula, 2Ωu cos(φ), corresponds to the Eötvös effect. The second term is a refinement that under normal circumstances is much smaller than the Eötvös effect</em></span><em>"</em></p></blockquote><p></p>
[QUOTE="Pdvdh, post: 1188468, member: 4191"] Watching the globe rotate on the north/south poles axis, the reason the vertical component of coriolis drift is largest at the equator, and null and void at the poles, also become obvious - in a manner not likely to be forgotten anytime soon. The equator is the farthest radius from the north/south axis. When the earth spins on that axis, the surface of the earth is rotating at the highest rate of speed at the equator - where the earth's surface is the farthest from the axis of rotation. Which means your target/game animal travels a greater distance between the time the bullet leaves the muzzle, and the bullet strikes the target/game animal. It'll now be much easier for me to remember the primary affecting aspects of both both components of coriolis. If I find myself fuzzy over horizontal and vertical coriolis in the future, I'll just remember the rotating globe. The eotvos component of vertical coriolis is pretty minor - not worth researching, unless you're a real nerd/geek. :) For all you nerds/geeks, it should be easy to follow this explanation from Wikipedia! "[B][I][FONT="Comic Sans MS"]The Eötvös effect is the change in perceived gravitational force caused by the change in centrifugal acceleration resulting from eastbound or westbound velocity. When moving eastbound, the object's angular velocity is increased (in addition to the earth's rotation), and thus the centrifugal force also increases, causing a perceived reduction in gravitational force. [/FONT][/I][/B][I][FONT="Comic Sans MS"] In the early 1900s (decade), a German team from the Institute of Geodesy in Potsdam carried out gravity measurements on moving ships in the Atlantic, Indian and Pacific Oceans. While studying their results the Hungarian nobleman and physicist Baron Roland von Eötvös (see Loránd Eötvös) (1848–1919) noticed that the readings were lower when the boat moved eastwards, higher when it moved westward. He identified this as primarily a consequence of the rotation of the earth. In 1908 new measurements were made in the Black Sea on two ships, one moving eastward and one westward. The results substantiated Eötvös' claim. Since then geodesists use the following formula to correct for velocity relative to the Earth during a measurement run.[/font][/I][FONT="Comic Sans MS"] a_r = 2 \Omega u \cos \phi + \frac{u^2 + v^2}{R}. [I]Here, a_r is the relative acceleration \Omega is the rotation rate of the Earth u is the velocity in latitudinal direction (east-west) \phi is the latitude where the measurements are taken. v is the velocity in longitudinal direction (north-south) R is the radius of the Earth [/I] [I]The first term in the formula, 2Ωu cos(φ), corresponds to the Eötvös effect. The second term is a refinement that under normal circumstances is much smaller than the Eötvös effect[/I][/FONT][I]"[/I] [/QUOTE]
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