STPM 物理问题马拉松！

huhuxboy

好像都没有提到stationary waves and inteference...

huhuxboy

原帖由 zxteh 于 2-11-2007 12:58 AM 发表
回复 #53 huhuxboy的帖子


question 1:

U ----> Pu + 2e-
i thinks the answer is C.

question 2:

mass defect=m(i)-m(f)    i:initial;f:final
           =(235.044u+1.009u)-(94.906u+138 ...

那么for Q2 energy per nucleon 是多少？？？
因为我老师做的方法怪怪的
请大家多多指教，小弟感激不尽

sylvia_r

这些都是STATIONARY WAVE的特征来的

zxteh

原帖由 huhuxboy 于 8-11-2007 10:17 PM 发表



那么for Q2 energy per nucleon 是多少？？？
因为我老师做的方法怪怪的
请大家多多指教，小弟感激不尽

回复 #62 huhuxboy的帖子

not energy per nucleon
is binding energy per nucleon...
u juz divide the binding energy u get by the no nucleon of nuclei..

in this case ,the nuclei is U-235,
then ,
Binding Energy per Nucleon=208MeV / 235
                             =0.885Mev per nucleon...

[ 本帖最后由 zxteh 于 13-11-2007 02:16 AM 编辑 ]

JohnChronox

原帖由 chunwei1088 于 12-9-2007 07:52 PM 发表
由于最近剑侠在＂暗拼＂，所以吩咐我来问以下这一题。。。

WHAT IS THE DIFFERENT BETWEEN INTERFERENCE（LIGHT WAVE） AND STATIONARY WAVE？？？

大家帮帮忙。。

第一，有点搞错了，light wave is a transverse wave, the differences between transverse wave and stationary wave are
1. Energy is transferred in a transverse wave
2. Transverse wave is a progressive wave with particles nearby DOESN'T occillates in phase and same amplitude as the wave, while partilces nearby stationary wave occillates in phase
这两个是最重要的分别

[ 本帖最后由 JohnChronox 于 15-11-2007 11:51 AM 编辑 ]

cold_spoon

An electron with mass, m and energy T collides with a hydrogen atom in the ground state. As a result, the hydrogen atom is excited and a photon with wavelength "v" is emitted when the atom returns to its ground state. If h is the Planck constant and c is the velocity of light, what is the velocity of the electron after the collision?

这题应该如何解？

sylvia_r

我觉得,一开始,ENERGY是T..
过后分一点给HYDROGEN,
ENRGY=T-hc/"v"
KE=T-hc/"v"
1/2mV^2=T-hc/"v"
V=[2(T-hc/"v")/m]^0.5
=[2(T"v"-hc)/"v"m]^0.5

对吗??

sylvia_r

"2. Transverse wave is a progressive wave with particles nearby occillates in phase and same amplitude as the wave, while partilces nearby stationary wave occillates not in phase"

Isn't it the particles nearby in sttionary waves are all in phase??

JohnChronox

谢谢你..
是我搞错了..
particles neighbouring stationary waves occilates in phase, particles neighbouring progressive waves doesn't occillates in phase

再见是为了明天

4        The engine of a car has a maximum output of 54 kW.  The air resistance acting on the car when it is moving with speed v is 2v^2.  The maximum speed which can be achieved by the car on a level road is
A        3.0 m s-1        
B        5.2 m s-1        
C        30 m s-1        
D        164 m s-1

[ 本帖最后由 再见是为了明天 于 16-11-2007 02:12 PM 编辑 ]

JohnChronox

C. P = Fv
   Given F = 2v^2
   P = 2v^3
   54000 = 2v^3
   v = 30ms-1

再见是为了明天

A flywheel rotates at a rate of n rotation per second.  If the mass and moment of inertia of the flywheel are M and I respectively, the work that should be done to stop the flywheel is  ?

再见是为了明天

A diesel engine does not need spark plugs for the combustion of a mixture of diesel and air in a cylinder.  Spontaneous combustion occurs when a high temperature is achieved through air compression.  If air with an initial temperature of 27 Celcius is compressed adiabatically to a final temperature of 681 Celcius, what is the ratio of the initial volume to the final volume?
        [Assume that air is a diatomic ideal gas]

JohnChronox

原帖由 再见是为了明天 于 16-11-2007 04:29 PM 发表
A flywheel rotates at a rate of n rotation per second.  If the mass and moment of inertia of the flywheel are M and I respectively, the work that should be done to stop the flywheel is  ?

Angular velocity = 2nPie rads^-1
rotational kinetic energy = [I(2nPie)^2] / 2
linear velocity = r x angular velocity
                     = 2nrPie
linear kinetic energy = [M(2nrPie)^2] / 2

Work must be done to stop flywheel = linear kinetic energy + rotation kinetic energy
                                                        = (I + Mr^2)(2nPie)^2 / 2       ------ Mr^2 = I
                                                        = 4I(nPie)^2
应该是这样吧？？错了请指正

再见是为了明天

i also have the same answer as u ...but the answer is 2I(n.pie)^2

this is objective question

JohnChronox

原帖由 再见是为了明天 于 16-11-2007 04:45 PM 发表
A diesel engine does not need spark plugs for the combustion of a mixture of diesel and air in a cylinder.  Spontaneous combustion occurs when a high temperature is achieved through air compressi ...

using equation TV^y-1 = constant
T1V1^1.4-1 = T2V2^1.4-1
(V1/V2)^0.4 = T2/T1
V1/V2 = (T2/T1)^2.5
           = (954/300)^2.5
           = 18.03

JohnChronox

原帖由 再见是为了明天 于 17-11-2007 12:19 PM 发表
i also have the same answer as u ...but the answer is 2I(n.pie)^2

this is objective question

如果是这样的话, 可能答案错吧..我懒得去check我有没有做错。。
还有。。。请用华文来post

sylvia_r

其实都没有LINEAR KE啊。。 那个FLYWHEEL 没有 LINEAR DISPLACEMENT吧。。

JohnChronox

又是你对了。。
可能我们都想太多了。。

sylvia_r

呵，我也是问PRO的朋友的