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发表于 4-10-2010 05:47 PM
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本帖最后由 nkrealman 于 4-10-2010 05:49 PM 编辑
为何magnitude是120°？
ultikiller 发表于 3-10-2010 02:38 PM 
你想像它在anticlockwise转着circle，所以那个direction是respect去右边120而不是左边60 |
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发表于 4-10-2010 09:27 PM
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你想像它在anticlockwise转着circle，所以那个direction是respect去右边120而不是左边60
nkrealman 发表于 4-10-2010 05:47 PM
为何要想像它在anticlockwise？原理在哪里？ |
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发表于 6-10-2010 09:15 PM
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form 6的课程有离心力=Centrifugal Force么？怎么我没看过的？
ultikiller 发表于 3-10-2010 02:37 PM 
没有。。。这是我在网上看到的。。。
只要提供给物体的力不够让物体做circular motion的话。。。
离心力就会跑出来
离心力也叫做惯性力(由inertia所造成的一种imaginery force) |
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发表于 13-10-2010 12:30 AM
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E_n=-(13.6)/n^2 eV
from the above equation write the expression for the energy states E_n of helium ion 4 +
2 He |
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发表于 6-11-2010 12:56 PM
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b) the ratio of the kinetic energy of the neutron to the kinetic energy of the
gold nucleus after the collision. |
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发表于 10-11-2010 02:23 PM
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One question here!!
You are 1.8 m tall and stand 3.0 m from a plane mirror that extends vertically upward from the floor. On the floor 1.5m in front of the mirror is a small table, 0.8m high. What is the minimum height the mirror must have for you to be able to see the top of the table in the mirror?? Help pls..I am stuck! |
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发表于 14-11-2010 04:21 PM
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谁有Ace Ahead Physics Volume2的书？
有的话可以看Exam practice 8 Question 2和11？
谢谢！ |
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发表于 18-11-2010 08:00 PM
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谁有Ace Ahead Physics Volume2的书？
有的话可以看Exam practice 8 Question 2和11？
谢谢！
醉痴雪 发表于 14-11-2010 04:21 PM 
>.< Ace Ahead always got that kind of errors... Follow your intuitions! |
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发表于 19-11-2010 05:22 PM
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回复 483# vick5821
I just try but I not sure it's right or not cuz u din provide the diagram..
W=V/r angular speed = 1.5/2=0.17rad s^-1
Anticlockwise. It's logic when u walk on a rim there is a frictional torque oppose your motion so the rim in opposite direction.
for b, I not so sure.
W=1/2 I W^2(final) - 1/2 I W^2(Initial)
=1/2(500 x 0.17^2 - 500 X 0)=7.23J
Provide me answer if I'm wrong. |
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发表于 20-11-2010 07:08 AM
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发表于 21-11-2010 05:56 PM
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今年好像没什么看到ramalan的东西，老师一直叫我们读好quantum，大家觉得怎样？ |
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发表于 23-11-2010 05:07 PM
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发表于 13-12-2010 09:54 PM
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Initially two electrons are fixed in place with a seperation of 2.0 x 10^-6 m. How much work must be we do to bring a third electron in from inifinity to complete an equilateral triangle?
Help pls!!! Urgent |
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发表于 17-12-2010 09:54 PM
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回复 496# vick5821
total work done = 2 X (e²/4πEr) ,
E=permittivity of free space |
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发表于 3-2-2011 08:55 PM
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It is suggested that the most effective way of stopping a car on a slippery road is to press and release the brakes repeatedly. Discuss whether this method will stop the car in a shorter distance as compared to when the brakes are applied
(i) very hard, so that the wheels stop rotating
ans: No, when the car skids, sliding friction which is lower than rolling friction acts.
WHY??? |
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发表于 15-2-2011 12:28 AM
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我可不可以请问，form 6的physics和form 5的是不是差很远？我对physics很有兴趣，可是form5时就觉得physics有点辛苦了。上了form6后如果我选physics,是不是等于自寻死路？ |
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发表于 15-3-2011 06:54 PM
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发表于 15-3-2011 07:13 PM
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回复 500# 苑静
你也是去年的spm毕业生吗？谢谢你的link... |
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发表于 15-3-2011 09:16 PM
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回复 501# Ponyjess
嗯对，我也在等成绩。不客气哦 =D |
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发表于 2-4-2011 01:28 PM
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来了个教了也听不懂的老师。。。怎么办？？T^T
不只是我有这问题，其他同学也是，而且做experiment时，这老师竟然用form5的方法写report。。。。==
我是不是完蛋了？？ |
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