From Terry.Moffat at rongotai.school.nz Mon Oct 12 22:44:34 2009 From: Terry.Moffat at rongotai.school.nz (Terry Moffat) Date: Tue, 13 Oct 2009 18:44:34 +1300 Subject: level 3 exams Message-ID: <4AD4CA91.DFDA.0008.1@rongotai.school.nz> Hi, earlier this year there was a comment that came out saying that Physics would be assessed on a full question basis rather than on its parts. Can any clarify how that might work? Does it mean that if there are say 4 main questions in the exam that there will be only four grades in the overall standard. I want to be able to give better guidance to my students. Ta Terry -------------- next part -------------- An HTML attachment was scrubbed... URL: From dhousden at xtra.co.nz Tue Oct 13 02:07:01 2009 From: dhousden at xtra.co.nz (David Housden) Date: Tue, 13 Oct 2009 22:07:01 +1300 Subject: level 3 exams In-Reply-To: <4AD4CA91.DFDA.0008.1@rongotai.school.nz> References: <4AD4CA91.DFDA.0008.1@rongotai.school.nz> Message-ID: <009a01ca4be4$8681f150$9385d3f0$@co.nz> Hi all There has been considerable confusion around this topic. There will be no change this year in physics (not the case in other subjects). The official situation is stated on the Secqual dated 3 July. It states: All questions will provide opportunity for all grades of performance - achievement, achievement with merit, and achievement with excellence. The question format will appear the same to candidates as in previous years with each question containing a number of part-questions. Each paper will be marked, as in previous years, with grades aggregated across the paper. This information updates Assessment Matters A2009/011 dated 3 April 2009. All the best David 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, 13 October 2009 6:45 p.m. To: phys-teach-talk at nzip.org.nz Subject: level 3 exams Hi, earlier this year there was a comment that came out saying that Physics would be assessed on a full question basis rather than on its parts. Can any clarify how that might work? Does it mean that if there are say 4 main questions in the exam that there will be only four grades in the overall standard. I want to be able to give better guidance to my students. Ta Terry -------------- next part -------------- An HTML attachment was scrubbed... URL: From ehall at sohs.school.nz Wed Oct 21 16:08:04 2009 From: ehall at sohs.school.nz (Emily Hall) Date: Thu, 22 Oct 2009 12:08:04 +1300 Subject: Problem from Level 2 NZIP exam Message-ID: <000301ca52a3$58da7860$0a8f6920$@school.nz> Hi I had a question about a problem from the level 2 NZIP exam we can?t seem to get straight in our minds here. The one where the guy hangs off the bar, his energy in that is 43J and the displacement of the bar is 0.14m so what is his mass? I worked it out and got 63kg which is what is in the marking schedule and that is all good ? using E=1/2kx2 and then F=-kx=mg. But then a student came to me with conservation of energy like mgh = mg(h-0.14) + 43 if you work it out though you get an answer of ? what the one is using the above method. We?ve gone through it several times and can?t figure out what the problem is. Can someone explain why they aren?t the same? Thanks Emily -- -- -------------------------------------------------------------- This email was sent using Telecom SchoolZone. www.schoolzone.net.nz This email has been scanned for viruses by Telecom SchoolZone, but is not guaranteed to be virus-free. -------------------------------------------------------------- -- ############################################################################### ###### Attention: The information contained in this message and or attachments is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any system and destroy and copies. ############################################################################### ###### -------------- next part -------------- An HTML attachment was scrubbed... URL: From francis.Bryden at stcuthberts.school.nz Wed Oct 21 17:31:19 2009 From: francis.Bryden at stcuthberts.school.nz (Bryden, Francis) Date: Thu, 22 Oct 2009 13:31:19 +1300 Subject: Problem from Level 2 NZIP exam In-Reply-To: <000301ca52a3$58da7860$0a8f6920$@school.nz> Message-ID: <6AC36C5F0F8E364CBEC8178DD499F3EFBBE93F4F58@stcc-exchange.stcuthberts.local> Hi Emily The question is quite tricky......... As he drops through a distance x, he loses GPE of mgx The energy stored in the bar is ? kx2 and since F=kx, and FW =mg the energy stored is ? mgx So he loses GPE of mgx and the bar gains EPE of ? mgx, so where is the missing ? mgx? The answer depends on how he moves down. if he grabs the bar and drops, its going to go into heat If someone slowly lowers him down as the bar deforms, they have to do work on him. The work they do is average force times x (Remember that the maximum force exerted by the bar is F=kx, the average as he moves from 0 to x is 1/2kx) The average force as they lower him would be ? mg, so the person lowering him would do ? mgx of work. The other point to note is that if he held the bar and is was unbent, and then he let go, the bar would initially bend a distance 2x, then oscillate and end up bent a distance x. Try it with a mass on a spring. Hope this is reasonably clear Thanks, ........ Francis Francis Bryden HoD Physics St Cuthbert's College 122 Market Rd Epsom 1021 PO Box 26 020 ph 64 09 520 4159 x 7808 -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of Emily Hall Sent: Thursday, 22 October 2009 12:08 p.m. To: phys-teach-talk at nzip.org.nz Cc: 'Mr Crawford' Subject: Problem from Level 2 NZIP exam Hi I had a question about a problem from the level 2 NZIP exam we can't seem to get straight in our minds here. The one where the guy hangs off the bar, his energy in that is 43J and the displacement of the bar is 0.14m so what is his mass? I worked it out and got 63kg which is what is in the marking schedule and that is all good - using E=1/2kx2 and then F=-kx=mg. But then a student came to me with conservation of energy like mgh = mg(h-0.14) + 43 if you work it out though you get an answer of ? what the one is using the above method. We've gone through it several times and can't figure out what the problem is. Can someone explain why they aren't the same? Thanks Emily -- -- -------------------------------------------------------------- This email was sent using Telecom SchoolZone. www.schoolzone.net.nz This email has been scanned for viruses by Telecom SchoolZone, but is not guaranteed to be virus-free. -------------------------------------------------------------- -- ############################################################################### ###### Attention: The information contained in this message and or attachments is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any system and destroy and copies. ############################################################################### ###### ________________________________ Please consider the environment before printing this email -------------------------------------------------------------------------------- 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 or contacting helpdesk at stcuthberts.school.nz, and deleting it from your computer. Messages sent to and from us may be monitored. -------------- next part -------------- An HTML attachment was scrubbed... URL: From xtr118950 at xtra.co.nz Thu Oct 22 14:12:46 2009 From: xtr118950 at xtra.co.nz (Paul King) Date: Fri, 23 Oct 2009 10:12:46 +1300 Subject: Elastic and gravitational energy "mismatch" Message-ID: The elastic potential energy stored in a stretched spring ( or a bent bar ) at equilibrium is always half of the gravitational potential energy lost by the mass whose moving down has caused the spring to stretch. The "missing" energy goes into heating the spring, or (as Francis has said ) into heating something else if the falling mass has been lowered with the help of a force other than gravity. This apparent mismatch between the lost GPE and the EPE gained by the spring should be made obvious to the students, probably by way of calculations followed by the question " How do we explain this?" An answer of " The spring gains heat energy as well as elastic energy " will probably be enough at this stage - everyone should be familiar enough with repeatedly bending a paperclip till it snaps and knowing how warm it gets, to feel cheerful about a stretched spring warming up. Paul King From ehall at sohs.school.nz Thu Oct 22 14:32:36 2009 From: ehall at sohs.school.nz (Emily Hall) Date: Fri, 23 Oct 2009 10:32:36 +1300 Subject: Elastic and gravitational energy "mismatch" In-Reply-To: References: Message-ID: <000001ca535f$2d4ed4e0$87ec7ea0$@school.nz> Francis/Paul Thanks for the responses - both of us here had thought Energy loss through heat was involved but had not realised that 1/2 the Energy would go to heat. Thanks Emily -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of Paul King Sent: Friday, 23 October 2009 10:13 a.m. To: phys-teach-talk at nzip.org.nz Subject: Elastic and gravitational energy "mismatch" The elastic potential energy stored in a stretched spring ( or a bent bar ) at equilibrium is always half of the gravitational potential energy lost by the mass whose moving down has caused the spring to stretch. The "missing" energy goes into heating the spring, or (as Francis has said ) into heating something else if the falling mass has been lowered with the help of a force other than gravity. This apparent mismatch between the lost GPE and the EPE gained by the spring should be made obvious to the students, probably by way of calculations followed by the question " How do we explain this?" An answer of " The spring gains heat energy as well as elastic energy " will probably be enough at this stage - everyone should be familiar enough with repeatedly bending a paperclip till it snaps and knowing how warm it gets, to feel cheerful about a stretched spring warming up. Paul King _______________________________________________ Phys-teach-talk mailing list Phys-teach-talk at nzip.org.nz http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz -- -------------------------------------------------------------- This email was sent using Telecom SchoolZone. www.schoolzone.net.nz This email has been scanned for viruses by Telecom SchoolZone, but is not guaranteed to be virus-free. -------------------------------------------------------------- -- ############################################################################### ###### Attention: The information contained in this message and or attachments is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any system and destroy and copies. ############################################################################### ######