[meteorite-list] A "Strike" with a spare ball
From: Rosemary Hackney <ltcrose_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:45 2004 Message-ID: <001501c400e5$ecd7e860$187dd6d1_at_default> This is a multi-part message in MIME format. ------=_NextPart_000_0012_01C400B3.9183DAA0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable hmmmm.. In a vacuum, Galileo proved that a feather and a rock fell at = the same rate. 32 ft per second per second. ( gravity )=20 The difference outside of a vacuum depends on the density of air i.e sea = level.. or airplane altitude.. Air currents.. temperature and shape of = the item. Terminal velocity for a skydiver in vertical position is _at_ 180 mph. = Tracking ( delta position) maybe _at_ 200mph. by the by.. My bro was a champion flour bomber from his little Grummen.( = Ruffles, cuz she had ridges) :-). Rosie ----- Original Message -----=20 From: MexicoDoug_at_aol.com=20 To: ROBERT.D.MATSON_at_saic.com=20 Cc: meteorite-list_at_meteoritecentral.com=20 Sent: Tuesday, March 02, 2004 9:50 PM Subject: Re: [meteorite-list] A "Strike" with a spare ball Hola Rob, You're right about the terminal velocity of a chondrite, in the shape = of a bowling ball being much faster than a conventional bowling ball. = This might still be a little counter intuitive, but, here are some 9 = inch diameter bowling ball terminal velocities (there's a lot of algebra = behind all the numbers that follow): Doug's really heavy 14 pounder (6.35 kg): 153 mph (69 m/s) Rob's super duper heavy 16 pounder (7.26 kg): 164 mph (73 m/s) A bowling ball with a density of 2g/mL =3D 12.51 kg =3D 27.6 pounds: = 215 mph (96 m/s) Typical chondrite ball _at_ 3.65 g/mL (50.3 pounds or 22.83 kg): 291 mph = (130 m/s) Iron meteorite ball _at_ 8.0 g/mL (110.3 pounds or 50.0 kg): 431 mph = (192 m/s) Shield shaped Iron (Cabin Creek AR): 300 mph (134 m/s) Oriented fat beer can shaped Iron at 50 kg (length =3D 3 times = diameter): 700 mph (312 m/s) Cabin Creek shaped Chrondrite: 202 mph (90 m/s) Oriented fat beer can chrondrite as above: 473 mph (211 m/s) So for a bowling ball shape, it would actually take an iron to achieve = the 140 m/s, an ordinary chondrite falls somewhat slower, in the shape = of a bowling ball. Could an ordinary Doug's bowling ball fall at the rate of a chondrite? = Maybe, at the limits. We have focused more on mass for the given cross = sectional area. But to fall at the same terminal rate, all that is = required is the same ratio of sqrt(mass)/sqrt(X-area) or really just = mass divided by area being the same. So, if it is twice the density, it = needs to be cut in half. Could an Iron fall at the same rate of the = ordinary bowling ball? Probably not, but for illustration, let's = consider Cabin Creek, which is quite close to the 50 kg - the same size = as our bowling ball - and a wonderful oriented shield shape I'd say = around the dimension ratio 33 X 33 X 10. That actually gives around = double the surface area as the spherical solid bowling ball shape, so it = probably fell at about "only" 300 mph (134 m/s), close to a bowling ball = chondrite. In the other hand a cylindrical shape (I arbitrarily set the = length three times the diameter. Of course there are other considerations like the frictional ablation = shaping, which is why cylinders turn into nosecones and bullets, and it = is no wonder that the Cabin Creek sample was know to be hot upon fall. = All the acceleration due to gravity holding back a 50 kg mass of iron = several hundred miles per hour is dissapated into heat. Alternately = nosecones are more likely to be cool and also with less thumbprinting. The table above summarizes all my calculations, maybe there is an = error, but I hope not. This should clear up free fall of stones that = lose their "cosmic velocity" as well as for bowling balls, and how it = fits in. A person typically free falls at 110 mph or so thought they = can double that by playing with orientation. Ha. The calculations also = showe this doubling effect for likely masses. Keep in mind non iron = meteorites are practically never going to stand the shear frictional = forces of shield shapes and "explode" into pieces. Also for fun, an = oriented bowling ball that fractures in exactly two hemispherical pieces = traveling terminally at 150 mph will leave the two fragments at a = terminal rate of ... 106 mph a piece. That's probably why "explosions" = seem to brighten fireballs. Suddenly the greater surface area for the = same total mass steps up the overal frictional energy released and the = meteors slow down from an instantly greater potential. I get into this stuff. That's why I liked the bowling ball expt. = which really sounds like an excuse for some fun. Saludos Doug Dawn Mexico =20 En un mensaje con fecha 03/02/2004 7:26:12 PM Mexico Standard Time, = ROBERT.D.MATSON_at_saic.com escribe: Hi Doug, =20 Good point on the density of a bowling ball. Intuitively, I would = have guessed the density was around 2 g/cm^3, when in fact it is barely above 1 = g/cm^3 -- about 1.15 for a 16-lb ball (the mass I was assuming). An ordinary = chondrite of the same size would weigh close to 50 lbs! So yes, air friction = is going to be a serious factor, and a bowling ball isn't going to have a chance = of reaching the terminal velocity of a chondrite (let alone that of an iron). =20 To do this experiment properly, then, they're going to need to drop = an object of the proper density. --Rob ------=_NextPart_000_0012_01C400B3.9183DAA0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Diso-8859-1"> <META content=3D"MSHTML 6.00.2800.1400" name=3DGENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=3D#ffffff> <DIV><FONT face=3DArial size=3D2>hmmmm.. In a vacuum, Galileo proved = that a feather=20 and a rock fell at the same rate. 32 ft per second per second. ( = gravity )=20 </FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>The difference outside of a vacuum = depends on the=20 density of air i.e sea level.. or airplane altitude.. Air currents.. = temperature=20 and shape of the item.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Terminal velocity for a skydiver = in vertical=20 position is _at_ 180 mph. Tracking ( delta position) maybe @ = 200mph.</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>by the by.. My bro was a champion flour = bomber from=20 his little Grummen.( Ruffles,</FONT></DIV> <DIV><FONT face=3DArial size=3D2>cuz she had ridges) :-).</FONT></DIV> <DIV><FONT face=3DArial size=3D2></FONT> </DIV> <DIV><FONT face=3DArial size=3D2>Rosie</FONT></DIV> <BLOCKQUOTE=20 style=3D"PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; = BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px"> <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV> <DIV=20 style=3D"BACKGROUND: #e4e4e4; FONT: 10pt arial; font-color: = black"><B>From:</B>=20 <A title=3DMexicoDoug_at_aol.com=20 href=3D"mailto:MexicoDoug_at_aol.com">MexicoDoug@aol.com</A> </DIV> <DIV style=3D"FONT: 10pt arial"><B>To:</B> <A = title=3DROBERT.D.MATSON_at_saic.com=20 href=3D"mailto:ROBERT.D.MATSON_at_saic.com">ROBERT.D.MATSON@saic.com</A> = </DIV> <DIV style=3D"FONT: 10pt arial"><B>Cc:</B> <A=20 title=3Dmeteorite-list_at_meteoritecentral.com=20 = href=3D"mailto:meteorite-list_at_meteoritecentral.com">meteorite-list@meteor= itecentral.com</A>=20 </DIV> <DIV style=3D"FONT: 10pt arial"><B>Sent:</B> Tuesday, March 02, 2004 = 9:50=20 PM</DIV> <DIV style=3D"FONT: 10pt arial"><B>Subject:</B> Re: [meteorite-list] A = "Strike"=20 with a spare ball</DIV> <DIV><BR></DIV><FONT face=3Darial,helvetica><FONT lang=3D0 = face=3DArial size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10">Hola Rob,<BR><BR>You're right about = the=20 terminal velocity of a chondrite, in the shape of a bowling ball being = much=20 faster than a conventional bowling ball. This might still be a = little=20 counter intuitive, but, here are some 9 inch diameter bowling ball = terminal=20 velocities (there's a lot of algebra behind all the numbers that=20 follow):<BR><BR>Doug's really heavy 14 pounder (6.35 kg): 153 mph (69=20 m/s)<BR>Rob's super duper heavy 16 pounder (7.26 kg): 164 mph (73 = m/s)<BR>A=20 bowling ball with a density of 2g/mL =3D 12.51 kg =3D 27.6 pounds: 215 = mph (96=20 m/s)<BR>Typical chondrite ball _at_ 3.65 g/mL (50.3 pounds or 22.83 = kg):=20 291 mph (130 m/s)<BR>Iron meteorite ball _at_ 8.0 g/mL (110.3 pounds or = 50.0=20 kg): 431 mph (192 m/s)<BR><BR>Shield shaped Iron (Cabin Creek = AR): 300=20 mph (134 m/s)<BR>Oriented fat beer can shaped Iron at 50 kg (length = =3D 3 times=20 diameter): 700 mph (312 m/s)<BR><BR>Cabin Creek shaped Chrondrite: 202 = mph (90=20 m/s)<BR>Oriented fat beer can chrondrite as above: 473 mph (211 = m/s)<BR><BR>So=20 for a bowling ball shape, it would actually take an iron to achieve = the 140=20 m/s, an ordinary chondrite falls somewhat slower, in the shape of a = bowling=20 ball.<BR><BR>Could an ordinary Doug's bowling ball fall at the rate of = a=20 chondrite? Maybe, at the limits. We have focused more on = mass for=20 the given cross sectional area. But to fall at the same terminal = rate,=20 all that is required is the same ratio of sqrt(mass)/sqrt(X-area) or = really=20 just mass divided by area being the same. So, if it is twice the = density, it needs to be cut in half. Could an Iron fall at the = same rate=20 of the ordinary bowling ball? Probably not, but for = illustration, let's=20 consider Cabin Creek, which is quite close to the 50 kg - the same = size as our=20 bowling ball - and a wonderful oriented shield shape I'd say around = the=20 dimension ratio 33 X 33 X 10. That actually gives around double = the=20 surface area as the spherical solid bowling ball shape, so it probably = fell at=20 about "only" 300 mph (134 m/s), close to a bowling ball = chondrite. In=20 the other hand a cylindrical shape (I arbitrarily set the length three = times=20 the diameter.<BR><BR>Of course there are other considerations like the = frictional ablation shaping, which is why cylinders turn into = nosecones and=20 bullets, and it is no wonder that the Cabin Creek sample was know to = be hot=20 upon fall. All the acceleration due to gravity holding back a 50 = kg mass=20 of iron several hundred miles per hour is dissapated into heat. =20 Alternately nosecones are more likely to be cool and also with less=20 thumbprinting.<BR><BR>The table above summarizes all my calculations, = maybe=20 there is an error, but I hope not. This should clear up free = fall of=20 stones that lose their "cosmic velocity" as well as for bowling balls, = and how=20 it fits in. A person typically free falls at 110 mph or so = thought they=20 can double that by playing with orientation. Ha. The = calculations=20 also showe this doubling effect for likely masses. Keep in mind = non iron=20 meteorites are practically never going to stand the shear frictional = forces of=20 shield shapes and "explode" into pieces. Also for fun, an = oriented=20 bowling ball that fractures in exactly two hemispherical pieces = traveling=20 terminally at 150 mph will leave the two fragments at a terminal rate = of ...=20 106 mph a piece. That's probably why "explosions" seem to = brighten=20 fireballs. Suddenly the greater surface area for the same total = mass=20 steps up the overal frictional energy released and the meteors slow = down from=20 an instantly greater potential.<BR><BR>I get into this stuff. = That's why=20 I liked the bowling ball expt. which really sounds like an excuse for = some=20 fun.<BR><BR>Saludos<BR>Doug Dawn<BR>Mexico = <BR><BR><BR><BR>En un=20 mensaje con fecha 03/02/2004 7:26:12 PM Mexico Standard Time,=20 ROBERT.D.MATSON_at_saic.com escribe:<BR> <BLOCKQUOTE=20 style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px = solid; MARGIN-RIGHT: 0px"=20 TYPE=3D"CITE"><BR></FONT><FONT lang=3D0 style=3D"BACKGROUND-COLOR: = #ffffff"=20 face=3DArial color=3D#0000ff size=3D2 FAMILY=3D"SANSSERIF" = PTSIZE=3D"10"=20 BACK=3D"#ffffff">Hi Doug,</FONT><FONT lang=3D0 = style=3D"BACKGROUND-COLOR: #ffffff"=20 face=3DArial color=3D#000000 size=3D3 FAMILY=3D"SANSSERIF" = PTSIZE=3D"12"=20 BACK=3D"#ffffff"><BR> <BR></FONT><FONT lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">Good point on = the density of a=20 bowling ball. Intuitively, I would have guessed</FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR></FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">the density was = around 2=20 g/cm^3, when in fact it is barely above 1 g/cm^3 --</FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR></FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">about 1.15 for a = 16-lb ball=20 (the mass I was assuming). An ordinary chondrite</FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR></FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">of the same size = would weigh=20 close to 50 lbs! So yes, air friction is going to</FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR></FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">be a serious = factor, and a=20 bowling ball isn't going to have a chance of reaching</FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR></FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">the terminal = velocity of a=20 chondrite (let alone that of an iron).</FONT><FONT lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR> = <BR></FONT><FONT=20 lang=3D0 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial = color=3D#0000ff size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">To do this = experiment=20 properly, then, they're going to need to drop an object</FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D3=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"12" BACK=3D"#ffffff"><BR></FONT><FONT = lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#0000ff = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10" BACK=3D"#ffffff">of the proper = density. =20 --Rob</FONT><FONT lang=3D0 style=3D"BACKGROUND-COLOR: #ffffff" = face=3DArial=20 color=3D#000000 size=3D3 FAMILY=3D"SANSSERIF" PTSIZE=3D"12"=20 BACK=3D"#ffffff"><BR></BLOCKQUOTE><BR></FONT><FONT lang=3D0=20 style=3D"BACKGROUND-COLOR: #ffffff" face=3DArial color=3D#000000 = size=3D2=20 FAMILY=3D"SANSSERIF" PTSIZE=3D"10"=20 BACK=3D"#ffffff"><BR></BLOCKQUOTE></FONT></FONT></BODY></HTML> ------=_NextPart_000_0012_01C400B3.9183DAA0-- Received on Wed 03 Mar 2004 01:07:51 AM PST |
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