From Jbull at stjohns-hamilton.school.nz Sun Mar 9 15:18:03 2008 From: Jbull at stjohns-hamilton.school.nz (John Bull) Date: Mon, 10 Mar 2008 08:18:03 +1300 Subject: momentum of sound Message-ID: <12D16F4BDB49284C927C4B1BE1CEC4A603F5F2@sj-dc2.internal.stjohns-hamilton.school.nz> At the risk of sounding dumb on Monday morning - can someone tell me whether sound has momentum, and if not - why not? (since it is moving particles) . This was a student's question relating to an experiment of an air rifle pellet hitting a block of wood. cheers John Bull St John's College Hamilton -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080310/8e9b1b1b/attachment.html From francis.Bryden at stcuthberts.school.nz Sun Mar 9 15:37:34 2008 From: francis.Bryden at stcuthberts.school.nz (Bryden, Francis) Date: Mon, 10 Mar 2008 08:37:34 +1300 Subject: momentum of sound In-Reply-To: <12D16F4BDB49284C927C4B1BE1CEC4A603F5F2@sj-dc2.internal.stjohns-hamilton.school.nz> Message-ID: The way I think of it is that sound transfers energy but not momentum. The individual air molecules have momentum, but for every molecule with +p there is another with -p. I suppose its possible for a compression to knock something over before the rarefaction has had time to pull it back On a related note. Many of you will have seen an "airzooka" that fires a toroid of air across the room. There is a transfer of air on this case, but why is it different to a loudspeaker that just vibrates the air Thanks ................ Francis Francis Bryden HoD Physics St Cuthbert's College 122 Market Rd or Box 26 020 Epsom Epsom Auckland 1051 Auckland 1344 New Zealand New Zealand ph: 63 9 5204159 ext 7808 fbryden at stcuthberts.school.nz -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of John Bull Sent: Monday, 10 March 2008 8:18 a.m. To: phys-teach-talk at nzip.org.nz Subject: momentum of sound At the risk of sounding dumb on Monday morning - can someone tell me whether sound has momentum, and if not - why not? (since it is moving particles) . This was a student's question relating to an experiment of an air rifle pellet hitting a block of wood. cheers John Bull St John's College Hamilton -------------------------------------------------------- This message (and any associated files) is intended only for the use of the individual or entity to which it is addressed and may contain information that is confidential, subject to copyright or constitutes a trade secret. If you are not the intended recipient you are hereby notified that any dissemination, copying or distribution of this message, or files associated with this message, is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and deleting it from your computer. Messages sent to and from us may be monitored. -------------------------------------------------------- This email has been checked by Symantec Mail Security for Exchange. 08:37:34 Mon 10 Mar 2008 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080310/174367b3/attachment.html From mlsavage at paradise.net.nz Mon Mar 10 12:11:55 2008 From: mlsavage at paradise.net.nz (Mike & Martha Savage) Date: Tue, 11 Mar 2008 05:11:55 +1300 Subject: momentum of sound In-Reply-To: References: <12D16F4BDB49284C927C4B1BE1CEC4A603F5F2@sj-dc2.internal.stjohns-hamilton.school.nz> Message-ID: <000e01c882c9$761abbc0$a5964eca@savage01> Seismic waves are sound waves. If you are ever in an earthquake, you will find that sound transfers momentum. That's why objects fall off shelves, etc. Cheers, Martha Savage _____ From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of Bryden, Francis Sent: Monday, 10 March 2008 8:38 a.m. To: phys-teach-talk at nzip.org.nz Subject: RE: momentum of sound The way I think of it is that sound transfers energy but not momentum. The individual air molecules have momentum, but for every molecule with +p there is another with -p. I suppose its possible for a compression to knock something over before the rarefaction has had time to pull it back On a related note. Many of you will have seen an "airzooka" that fires a toroid of air across the room. There is a transfer of air on this case, but why is it different to a loudspeaker that just vibrates the air Thanks ................ Francis Francis Bryden HoD Physics St Cuthbert's College 122 Market Rd or Box 26 020 Epsom Epsom Auckland 1051 Auckland 1344 New Zealand New Zealand ph: 63 9 5204159 ext 7808 fbryden at stcuthberts.school.nz -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of John Bull Sent: Monday, 10 March 2008 8:18 a.m. To: phys-teach-talk at nzip.org.nz Subject: momentum of sound At the risk of sounding dumb on Monday morning - can someone tell me whether sound has momentum, and if not - why not? (since it is moving particles) . This was a student's question relating to an experiment of an air rifle pellet hitting a block of wood. cheers John Bull St John's College Hamilton _____ This message (and any associated files) is intended only for the use of the individual or entity to which it is addressed and may contain information that is confidential, subject to copyright or constitutes a trade secret. If you are not the intended recipient you are hereby notified that any dissemination, copying or distribution of this message, or files associated with this message, is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and deleting it from your computer. Messages sent to and from us may be monitored. _____ This email has been checked by Symantec Mail Security for Exchange. 08:37:34 Mon 10 Mar 2008 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080311/9bec16ca/attachment.html From dhousden at xtra.co.nz Wed Mar 19 05:30:54 2008 From: dhousden at xtra.co.nz (David Housden) Date: Wed, 19 Mar 2008 22:30:54 +1300 Subject: Newton Plus Message-ID: <003301c889a3$eebc1fc0$cc345f40$@co.nz> Hi all Have a request from Wellington East Girls as below. Can anyone help please? Cheers David Hi David, Hope the year is going well for you. We have an increase in numbers doing L2 Physics and are 10 short of Newton Plus textbooks. They are now out of print. Do you, or anyone you have contact with have 10 spares, as I can't afford to change to a new one this year. Regards, Lorna -- Lorna Young HYPERLINK "mailto:lyoung at wegc.school.nz"lyoung at wegc.school.nz No virus found in this outgoing message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.21.7/1333 - Release Date: 18/03/2008 8:10 a.m. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080319/08cbbbe1/attachment.html From Terry.Moffat at rongotai.school.nz Mon Mar 31 21:01:30 2008 From: Terry.Moffat at rongotai.school.nz (Terry Moffat) Date: Tue, 01 Apr 2008 13:01:30 +1200 Subject: re mythbusters video Message-ID: <47F2322A.DFDA.0008.0@rongotai.school.nz> Hi, I hope someone can save me search time. Mythbusters did an experiment of firing a ball at 100 kph out the back of a moving vehicle travelling at 100 kph I gather it is somewhere on the net. Does anyone have the link? ta Terry Moffat From dhousden at xtra.co.nz Mon Mar 31 20:33:57 2008 From: dhousden at xtra.co.nz (David Housden) Date: Tue, 1 Apr 2008 13:33:57 +1300 Subject: re mythbusters video In-Reply-To: <47F2322A.DFDA.0008.0@rongotai.school.nz> References: <47F2322A.DFDA.0008.0@rongotai.school.nz> Message-ID: <001c01c89390$12c28210$38478630$@co.nz> Hi Terry I haven't heard that Mythbusters did this but check out http://www.youtube.com/watch?v=yPHoUbCNPX8 - fantastic despite the fact it is in Japanese (actually I think it makes the clip even better) - I showed this to a number of groups last year - very good clip. A nice extra question to ask is about energy in terms of where has the kinetic energy "gone". Cheers David -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of Terry Moffat Sent: Tuesday, 1 April 2008 2:02 p.m. To: phys-teach-talk at nzip.org.nz Subject: re mythbusters video Hi, I hope someone can save me search time. Mythbusters did an experiment of firing a ball at 100 kph out the back of a moving vehicle travelling at 100 kph I gather it is somewhere on the net. Does anyone have the link? ta Terry Moffat _______________________________________________ Phys-teach-talk mailing list Phys-teach-talk at nzip.org.nz http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz No virus found in this incoming message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.22.1/1352 - Release Date: 31/03/2008 10:13 a.m. No virus found in this outgoing message. Checked by AVG. Version: 7.5.519 / Virus Database: 269.22.1/1352 - Release Date: 31/03/2008 10:13 a.m.