这篇文章可以回答小孩子多大去国外读书好

北美枫叶

原帖由 dongma 于 2009-2-9 05:53 发表

                               
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孩子选的是Full IB, 第一学期是高一纯数学Math 10 Pure，现在是高二的纯数学Math 20 Pure IB，物理是Phys 15 IB,16开的大本，1000页，三年要修120学分。一天4节课，只能选4门课，再利用暑假选一门Social，这是孩子在高一现在的情况 ...

不太理解你说得full ib，怎么IB班还可以选么？你在哪个省呢？难道加拿大境内的教育有很大不一样么？你说得IB班毕业证是否就是那个全被美通用的？

dongma

原帖由 北美枫叶 于 2009-2-24 00:53 发表

                               
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不太理解你说得full ib，怎么IB班还可以选么？你在哪个省呢？难道加拿大境内的教育有很大不一样么？你说得IB班毕业证是否就是那个全被美通用的？

是在阿省。full ib就是所有的科目都是ib，毕业以后发一个全北美通用的Diploma。这边也有部分ib，就是只选某些科目的ib，毕业以后发一个Certificate，好像也是北美通用，就是含金量较Diploma少。有意ib的学生在阿省10年级第一个学期就进行一个申请的过程，在这个过程里，学校的ib委员会从你选择的量，科目，老师推荐和具有挑战性的ib asssignments的成绩来考虑，来决定是否能够吸入ib。选择还是比较严格和公平的。物理的ib一个年级670多人总共选了不到40人。具体的申请过程学校与学校之间还有差异，但是申请的方式在学校里面肯定能够问到。

dongma

在初中就是gifted 班，高中叫Full IB。据说Western Canada Sr High School 最后坚持下ib班的只有不到2个班，这是在卡城．

lucktj

dongma,谢谢，看来在国外上中学也不轻松，只不过不像国内的题海战术

dongma

An exploration of the relationship between the time of diffusion and surface area to volume ratio.

Purpose: The purpose of this experiment is to determine the influence of surface area to volume ratio on time of diffusion.

Background Information: The purpose of the experiment is to discuss the relationship between the rate of diffusion and volume. It is actually, a simulation of a cell. As we all know, cells are open and living systems. They need to exchange both matter and energy with the outside world. One particularly important way of exchanging matter is diffusion (which is the spontaneous process of particles moving from high concentrated area to low concentrated area by random particle movement). The time of diffusion is related with the surface area of the cell, so, if a cell wants to increase its rate of diffusion, it has to figure out a way to create maximum surface area with a limited amount of volume.

Mathematically, the “symptom” of achieving great surface area in a limited amount of volume is a high surface area-volume ratio. In this fraction, the numerator is the surface area while the denominator is the volume. If the volume stays the same but the surface area increases, the ratio would increase. The same thing will happen if the volume decreases while the surface area stays the same.

To calculate the surface area to volume ratio, we need to calculate the surface area to volume ratio. As we are using cubes, the surface area of the cube SA = 6s2, while the volume V = s3. By simplifying the rational expression that represent the surface area to volume ratio, we get SA/V = 6/s. According to this equation, one can easily see that the surface area to volume ratio is affected only by the side length of the cube, and the greater the side length, the smaller the surface area to volume ratio.

In this particular experiment, we are going to use agar to simulate cells, and by measuring the time of an obvious reaction caused by diffusion, we can estimate the rate of diffusion. The reaction we chose is a simple one. As we all know, phenolphthalein shows a color of pink in a base solution. When we add sodium hydroxide and phenolphthalein in the agar, and agar will show a color of pink. Then, we can soak them into hydrochloric acid. Hydrochloric acid can react with sodium hydroxide and remove the hydroxide ions inside the solution to neutralize the base. The reaction can be shown like this.

NaOH + HCl = NaCl + H2O

When hydrochloric acid diffuses, reacts with sodium hydroxide and finally reaches an equilibrium between the cubes and the solution outside (which is, must be an acid environment), there will be no free hydroxide ions inside the cubes. In an acid environment, phenolphthalein is colorless, thus, the cube would turn from pink to colorless. The less time it takes to become colorless, the faster the reaction and therefore the faster the diffusion.

Hypothesis: The smaller the volume of the cube is, the less time it takes to turn colorless.

Variables: Manipulated Variable: The dimension of the agar cubes
         Controlled Variables: Temperature, material of agar cubes, concentration of the hydrochloric acid.
         Responding Variables: The time of the completion of color change.

Material: 4 agar cubes (10 mm ×10 mm × 10 mm each), stopwatch, 0.1 mol/L HCl (aq), graduated cylinder, scalpel, spot plate, ruler, forceps.

Procedure: Step1: Take 4 agar cubes, cut one of them into 8 smaller cubes by halving every one of its dimension. Take one of the smaller cubes and cut them into 8 even smaller ones.
          Step2: Pour some hydrochloric acid into the spot plate; make sure that the hydrochloric acid can submerge the cubes when cubes are put into the spot plate.
          Step3: Put one big agar cubes into the plate. Start to measure time. Stop the stopwatch when the agar cubes become exactly colorless. Record the time.
          Step4: Prepare a new plate. Repeat step 2 and 3 with other big cubes.
          Step5: Repeat step 2 to 4 with medium-sized and smaller-sized cubes.

Observation:
Relative size of the cubes        Trials        Time it takes for the agar cubes to turn completely colorless
(Minute: second: millisecond
±0.05)        Dimension of the agar cubes (in centimeters, ±0.05)
Big        Trial 1        3 : 42 : 76        0.70×0.70×0.70
        Trial 2        6 : 08 : 13        0.80×0.80×0.80
        Trial 3        5 : 44 : 69        0.90×0.90×0.90
Medium        Trial 1        2 : 15 : 54        0.35×0.35×0.35
        Trial 2        1 : 13 : 22        0.35×0.35×0.35
        Trial 3        1 : 30 : 56        0.35×0.35×0.35
Small        Trial 1        0 : 27 : 10        0.165×0.165×0.165
        Trial 2        0 : 15 : 75        0.165×0.165×0.165
        Trial 3        0 : 30 : 34        0.165×0.165×0.165
Table 1: Dimension of the cubes and the time it takes to become completely colorless
Note that the agar cubes after the experiment is not necessarily colorless, but shows a shade of yellow in it. This is because the agar is not completely colorless.

Analysis: First, we need to calculate the surface area to volume ratio of those agar cubes. Let’s take the example of the 0.70×0.70×0.70 cube. The surface area of the cube is:

SA cube = 6 s2 = 6 × (0.70 cm)2 = 2.94 cm2

The volume of the cube is:

V cube = s3 = (0.70 cm)3 = 0.343 cm3

The surface area to volume ratio is SA cube / V cube = (2.94 cm2) / (0.343 cm3) ≈ 8.57 cm-1

All the surface area to volume ratio is calculated in the table below:

Relative Size        Side length of the cubes in cm        Surface area of the cube in cm2        Volume of the cube in cm3        Surface area to volume ratio in cm-1
Big        0.7        2.94        0.343        8.57
        0.8        3.84        0.512        7.5
        0.9        4.86        0.729        6.67
Medium        0.35        0.735        0.042875        17.14
        0.35        0.735        0.042875        17.14
        0.35        0.735        0.042875        17.14
Small        0.165        0.16335        0.004492125        36.36
        0.165        0.16335        0.004492125        36.36
        0.165        0.16335        0.004492125        36.36
Table 2: Surface area, volume and surface area to volume ratio of the cubes


We can see that the bigger the side length of the cube is, the smaller the surface area to volume ratio is. In fact, the relationship is precisely r = 6/s, the graph is shown exactly above. Now, what about the time required to turn completely colorless, that is, the efficiency of diffusion? We now build a chart to show the relationship between time and surface area to volume ratio.


The trend line in the graph is similar to the graph of the function y = x-1. Using the regression analysis method, we can determine that the equation of the best fit line is t = 3480.2537x-1 – 75.56, where r ≈ 0.8997 > 0.602. So there is 95% chance that the relationship is genuine.

According to the property of monotony of the type of function, we can determine that while x is greater than 0, when x increases, responding variable t decreases. Thus, using mathematical method, we can determine that the greater the surface area to volume ratio, the less time it needs for diffusion to complete.

Conclusion: The greater the side length is, the less the surface area to volume ratio is, and the more time of diffusion it needs.

Evaluation: The main source of error of this experiment is that the standard for “colorless” may be different in different trials. During our experiment, the pinkish color become very thin in the end, that sometimes it’s hard to tell whether it’s colorless or not. Also, when different member of the experiment team checks whether the cubes are colorless or not, there standard might be different. A cube can appear to be colorless to somebody, while someone else might spot a shade of pink in it. We think that the time variation caused by this factor could be as much as 10 seconds, which will affect the coefficient “r” in the regression analysis part. If the variation is great enough, r might be below the rate of 0.602, causing the equation to lose its meaning.

The impact of this source of error may be reduced by asking the same person to determine whether these cubes are colorless or not. The standard of one person on this issue, although still will be slightly different, will be almost the same with different trials. Maybe the time he decided is still different from the precise time of the last OH- ion being eliminated, but because the standard is the same, the whole trend won’t be affected.

北美枫叶

原帖由 dongma 于 2009-2-24 07:38 发表

                               
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是在阿省。full ib就是所有的科目都是ib，毕业以后发一个全北美通用的Diploma。这边也有部分ib，就是只选某些科目的ib，毕业以后发一个Certificate，好像也是北美通用，就是含金量较Diploma少。有意ib的学生在阿省10年级第一 ...

我们也在阿省呀，这个月出才去一所附近的高中参观IB班的OPEN  HOUSE，听校长的说法也不觉得有什么特别的呀。还有，校长根本就没说什么FULL IB的，只说在学区里、成绩合格的直接就可以上；不在学区里要考试、还要交PASTPORT什么的。

北美枫叶

原帖由 dongma 于 2009-2-24 07:43 发表

                               
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在初中就是gifted 班，高中叫Full IB。据说Western Canada Sr High School 最后坚持下ib班的只有不到2个班，这是在卡城．

我女儿目前在初中，就叫AC班，没有其他说法。这是在埃德蒙顿。各地叫法不一样了。看来卡城的叫法更接近安省。

一杯清茶

小清茶刚刚报了Full IB获得批准，所以知道一点，补充一下。

Full IB向相对于Partial IB而言的，后者只是相当于提前把大一的部分课程修读了，可以省去不少时间和金钱，大学可以提前毕业。而前者除了有上述好处外，更重要的是Full IB成绩直接用于大学录取参考（美国），有Full IB成绩的申请人不必再提供normal成绩单（加拿大），能提供较好Full IB成绩的申请人申请成功率较高。

dongma

数学考试共3道大题,在家里做的,要考察孩子是否具备研究性学习的能力，给留出的时间是１星期，假如上IB太难的话，对孩子也不好。物理班共２班，孩子的班里只有１２个人。假如不选IB,毕业时，发阿省的高中毕业证，假如不去美国上大学，选不选IB,都没有关系。我问过不少孩子，有很多都不知道。高中的数学共分３种，有IB 数学，有应用数学，还有更简单的，我说不上名字,孩子说是数学14.

dongma

It is with our sincerest congratulations that we are able to offer you a placement within SWC 's IB program.Your application went to our selection committee and was looked at the basis of the following criteria:
SWC high school的那个机构叫selection committee.

dongma

15楼的那个帖子打上的是学校的原信，其中的７项，就是他们对申请IB课程学生的要求。也可能不同的学校不同的要求。

njyouyang

我对你的观点表示怀疑，你的数据从何而来？？？是专家调查统计的吗？？？

未飘落的雪

俺孩子的成绩够上FULL IB, 可他只选部分的IB班上，侧重于他喜欢的SCIENCE和MATH, 他说全上了是自虐。这孩子，上进心不够。

dongma

第一页里的那个英语人物分析的短文，老师给了６５分！老师说写作有问题。这是家长见面会上老师给说的。虽然英语综合成绩还可以，但也不高。老师安慰我说他的英语还是strong.法语老师的评价还是不错的。

dongma

Body Paragraph 1                                                                        
Lady Capulet’s misfortune lies in the deception of her daughter towards her. She wants the best for her daughter; she wants Juliet to “…share all that [Paris] doth possess / By having him, making [herself] no less.” (1.3.99-100). However, Juliet doesn’t like her proposes and instead of refusing her mother’s offer directly, she says that she’ll “…look to like, if looking liking move.” (1.3.103). This hidden tone of disobedience and the ambiguous response shows Juliet’s hostile attitude towards her mother and Juliet’s reluctance of marrying so early is hidden well in the words. In the haste before the big Capulet’s party, it is impossible for Lady Capulet to comprehend the true meaning of theses words, and thus, she is deceived. She doesn’t learn about Juliet’s unwillingness to marry Paris until Juliet openly expressed herself two days later. Lady Capulet doesn’t know about Romeo and Juliet’s marriage until their death, and after Tybalt’s death, she thought Juliet is “evermore weeping for [her] cousin’s death.” (3.5.71). There is no way that she can learn about the true reason for Juliet’s grief, which is Romeo’s banishment from Verona. As she tries to comfort Juliet, she says that she will have Romeo poisoned. Here, Juliet responded that “… [she] never shall be satisfied / With Romeo till I behold him—dead— / Is my poor heart, so for a kinsman vexed.” (3.5.98-100). Lady Capulet heard what she expected to hear, that Juliet “never shall be satisfied with Romeo till [she] behold[s] him dead.” But Juliet actually meant that she “never shall be satisfied with Romeo till [she] behold[s] him. Dead is [her] poor heart, so for a kinsman vexed.” The only time Juliet is straight forward to her mother is the time she told her that “[Pairs] shall not maker [her] there a joyful bride.” (3.5.122). Even then, she doesn’t tell her mother about the secret marriage. Instead, she said that “[she] will not marry yet, and when [she] do[es] she swear[s] / It shall be Romeo, whom [Lady Capulet] know[s] [she] hate[s], / Rather than Paris…” (3.5.126-128). This creates an irony: Juliet will definitely marry Romeo rather than Paris, but her mother is not aware of that, and she thinks that Juliet hates Paris so much that she would rather marry her enemy (Romeo) than Paris. From the conversations between Juliet and Lady Capulet throughout the play, we can see that Juliet is extremely deceitful, which makes it impossible for Lady Capulet even to know and protect her own daughter. This lack of understanding between she and her daughter is one of the reasons Lady Capulet is unfortunate and deserves sympathy.


Comment Paragraph:
In Body Paragraph 1, I tried to find enough evidence to support the fact that Juliet is deceitful. I think I did a fairly good job embedding the quotations into my paragraph. I organized my paragraph in the order of the play and logically (I hope). I didn’t do well in the tone of my paragraph. Sometimes it’s a little biased and a little too casual.

dongma

这是《Romeo and Juliet》里的人物分析，恳请热心人斧正。可给我悄悄话啊。先谢谢了。

dongma

The effect the pulling length has on the speed of air doughnut fired by an air-cannon

Physics 15 IB Period 4 of School Year 2008-09
2009-4-2

Problem
What effect does the pulling length of an air-cannon have on the speed of air doughnut fired by the air-cannon?
Introduction
First, the mechanism and structure of an air-cannon must be stated clear. An air-cannon’s components include a big box which has a round hole on one side and the surface opposite the hold dismantled, a large and strong plastic bag, a small plastic bag, four rubber bands, and sticky tape. When constructing the air-cannon, we cover the dismantled surface with the big plastic bag, use the sticky tape to hold it, then with a rubber band, the small plastic bag and some sticky tape, make a knob at the middle of the big plastic bag. Next, attach one end of the other rubber bands to the knob, the other ends to the inside of the box. Make sure that the rubber bands are pulled tight.
Here’s how an air-cannon works. When you pull the knob back, the rubber bands are stretched and the interval volume of the air-cannon increases. When you release the knob, the tension of the rubber bands will pull the knob back to where it originally was. As the knob returns to its original position, the internal volume of the air-cannon decreases suddenly, and air was pumped out of the air-cannon through the hole. We call this invisible “clump” of air an air doughnut. This can be explained by the Ideal Gas Law:

Where p is the absolute pressure of the gas, V is the volume of the gas, n is the number of moles of gas, R is the universal gas constant, and T is the absolute temperature of the gas. As we pull back the knob, the volume of air in the box increases. Since T and p must stays constant, R is a constant, so n must increase. Air flows into the air-cannon. As the knob is released, the volume V decreases, and the number of moles of air, n decreases—air flows out of the air-cannon. Although the Ideal Gas Law only works with Ideal Gas, in most cases it’s a good approximation.
The whole idea of an air-cannon and the application of Ideal Gas Law is not new. In fact, the human kind has been applying this technology in military for hundreds of years. In third century BC, Ctesibius of Alexandria wrote the idea of a cannon using compressed air in his works. After the ancient Chinese invented the primitive form of gunpowder around 10th century, they quickly applied it to military use. The earliest known depiction of a cannon is a sculpture found in Sichuan Province, China in the 12th century. After the Arabs brought gunpowder to Europe,  the Europeans improved the technology and artillery became an essential element of modern wars. The invention and application of cannons have dramatically affected the course of human history.
Cannons using gunpowder generally works this way: the cannonball will be placed at the front, while gunpowder will be placed at the behind. When someone lights the gunpowder, it burns quickly and the chemical energy stored in the powder is transformed into heat. The temperature of air in the cannon would increase dramatically in just a matter of seconds. As the internal volume of the cannon stays fairly constant, then according to the Ideal Gas Law, the internal pressure of the air within the cannon will increase and propel the cannonball out of the muzzle in a relatively great speed.
In our case, we still apply the Ideal Gas Law for the firing process. However, instead of using the gunpowder to increase the temperature, we decreased the volume of the air-cannon to increase the pressure and instead of shooting a solid cannonball, the air-cannon shoots invisible air “cannonballs”. The basic idea works the same.
We now have enough information to make a prediction. If the pulling length of the air-cannon increases, then the speed of the air doughnut will also increase; they are directly proportional. Because according to Hooke’s Law, the restoring force of the rubber bands is directly proportional to the length it is pulled. Since theoretically,  the force and the pulling length have a linear relationship, and the force is 0 N if the pulling length is 0, so the average force is directly proportional to the maximum force, and thus, directly proportional to the pulling length, or symbolically:
      
      
As we regard the air doughnut as a mass point, we can apply the impulse-momentum theorem:

Since mass m is constant, if we assume that the time interval during which the force is applied, then we get the relationship:

Since   is 0, plus the proportionality relationship between average force and the pulling length, we get the relationship:

If we plot this relationship on a graph, we get an oblique straight line passing through the origin:

Impulse is defined as , or in a simpler form:  . If we manipulate the above equation by applying Newton’s Second Law of Motion: , we have:

This is called the impulse-momentum theorem. In general, it states that the impulse equals change in momentum.
As you can see in the predictions, the important assumptions of this lab includes: We assume that the rubber bands can be approximated by Hooke’s Law; we assume that the Ideal Gas Law can be used to approximate the air in the air-cannon; we assume that the air-doughnut has no volume and we assume that the air doughnut travels in a uniform motion.
To test our predictions, we set a distance for the air doughnut to travel, then we fire the air-cannon, and measure the time it takes for the air doughnut to cover the distance. Since we assume the air doughnut travels in uniform motion, and the distance is fixed, we can then calculate the speed of the air doughnut.
The independent variable of this experiment is the pulling length of the air-cannon, the dependent variable is the speed of the air doughnut, and important fixed variables include: the size of the air-cannon muzzle, the same air-cannon, the same person pulling the air-cannon and the same target for the air-cannon.
Materials
        An air-cannon
        A stand
        A piece of tissue paper
        Five meter measuring tape
        Stop watch
        Sticky tape
        A piece of string (at least 50cm long)
        A table big enough to put the air-cannon on
Procedure
Step 1: Tape the air-cannon to the table.
Step 2: Use the measuring tape, measure 4.00 m horizontally away from the “muzzle” of the air-cannon.
Step 3: Place the stand on the 4.00 m mark. Make sure that the muzzle of the air-cannon is aiming at the stand.
Step 4: Tie a piece of tissue paper on a string, then tie the other end of the string to the stand.
Step 5: Fire the air-cannon. Make sure that the tissue moves, which means that the air doughnut can hit the tissue. If it doesn’t move, then arrange the aiming direction of your air-cannon and repeat this step until the tissue can be moved by the air doughnut.
Step 6: Pull the knob back 15 cm, and then release the knob. Start timing with the stop watch the moment the knob is released, and stop timing when you see the tissue paper move. Record the time measurement.
Step 7: Repeat Step 6 four more times.
Step 8: Repeat Step 6-7 five more times, but each time, pull back the knob 20cm, 25cm, 30cm, 35cm and 40cm correspondingly.
Step 9: Calculate the speeds using the formula , where x is the distance traveled, v is the speed and t is the time interval. Then find the average speed and standard deviation of the speed of air doughnut.

Observations
Pulling length, x (cm±0.05cm)        Time it takes for the air doughnut to reach the tissue, t (s±0.005s)
        R1        R2        R3        R4        R5        R6
15.00        1.54        1.34        1.65        1.62        1.76        1.63
20.00        1.18        1.15        1.10        1.32        1.23        1.35
25.00        0.81        0.72        0.85        0.78        0.76        0.85
30.00        0.64        0.62        0.65        0.65        0.66        0.64
35.00        0.56        0.53        0.52        0.55        0.52        0.55
40.00        0.40        0.43        0.39        0.46        0.42        0.50
Table 1. Pulling length of the air-cannon and the time it takes for the air doughnut to reach the tissue
The observations of this experiment are all in Table 1. The pulling length ranges from 15.00 cm to 40.00 cm, and the time intervals range from 0.39 s to 1.76 s. There is an obvious trend among the data: as the pulling length increases, the time decreases.
Analysis
Pulling length, x (cm±0.001cm)        The speed of the air doughnut calculated, v (m/s)        Average values of speed vave (m/s)        Standard deviation of speed (m/s)
        R1        R2        R3        R4        R5        R6               
15.00        2.60         2.99         2.42         2.47         2.27         2.45         2.53         0.244
20.00        3.39         3.48         3.64         3.03         3.25         2.96         3.29         0.261
25.00        4.94         5.56         4.71         5.13         5.26         4.71         5.05         0.334
30.00        6.25         6.45         6.15         6.15         6.06         6.25         6.22         0.134
35.00        7.14         7.55         7.69         7.27         7.69         7.27         7.44         0.238
40.00        10.00         9.30         10.26         8.70         9.52         8.00         9.30         0.838
Table 2. Pulling length of the air-cannon, the speeds of the air doughnut and their average and standard deviation
Sample Calculations for Speed Values:
Known:  ,  .
Unknown:  

Sample Calculations for Statistics:
Known:  ,   See Table 2.
Unknown:  ,  


  
Regression Calculations:
Known:  ,  ,   See Table 2.
Unknown: In  ,  ,  ,  


            


               

From Table 2 and Figure 2, we can see that the average speed and the pulling length have a linear relationship, but the line’s v-intercept is not close enough to 0 to be ignored.
Discussion
In this experiment, we used an air-cannon to fire air doughnuts toward a piece of tissue and measured the time the air doughnut traveled. By making the air doughnut move the tissue, we can study the motion of an invisible object—air doughnut—by studying its effect. It’s a very common and effective way scientists learn about the world.
The variations are relatively small. Even after the calculations, the errors are still, all under 10%. But when applying regression methods, we found that the regression line has a non-zero v-intercept. This is unexpected and intuitively doesn’t make sense. The air doughnut will have no net movement—thus having a speed of 0 m/s—if the air-cannon isn’t pulled back. However, this might be explained by the error in our measurements.
There are many sources of error which might have contributed to the fact that the regression line doesn’t pass through the point of origin. One significant source of error is that the time the air doughnut traveled is too small to be measured accurately, especially with longer pulling lengths. This is a random source of error because we do not know if this source of error will increase or decrease our measurements. This error is of great significance. It might be reduced by increasing the distance between the stand and the air-cannon.
Another source of error is the friction between the air doughnut and the air surrounding it. This is a systematic source of error and it will always increase our time measurements. This error is of great significance, and it is a very important reason for the negative v-intercept, especially when the regression line can be regarded as a line passing through the origin vertically translated downward. Unfortunately, there is no way to reduce this source of error in this air-cannon system.
Another source of error is that the air-cannon is not pulled back the same amount in each level of manipulated variable. This is classified as a random source of error since there is no way that we can learn whether this source of error will increase or decrease our time measurements. This source of error is of minor significance and it can be reduced by rechecking the pulling length before firing the air-cannon.
The fact that the tissue paper will not return to its exact position every time it was blasted is also a source of error. This can be classified as a random source of error because its effect on our measurements is unknown. This source of error is of minor significance and unfortunately there is no way to reduce the impact of this source of error.
Despite all these sources of errors, the results generally supported our hypothesis. The prediction that the speed of air doughnut will increase with the pulling length is supported, but the prediction that they are directly proportional is not supported, due to the non-zero v-intercept of the regression line.
So now, the question can be answered. The speed of air doughnut is partially proportional with the pulling length. If the pulling length increases, the speed of air doughnut will also increase.
Conclusion
The hypothesis is partially supported. The pulling length of the air-cannon is partially proportional to the speed of the air doughnut, and as the pulling length increases, the speed also increases. Since the standard deviations are generally small, percent errors are all under 10% and the regression coefficient   is very close to 1, the results of this experiment are generally reliable.
Acknowledgements
I’d like to thank my instructor Dr. T Pike who provided guidance during the whole process.
I’d also like to thank my partners Jimmy Wang and Harry Du who provided lots of insightful ideas in our experiment. Without them, I couldn’t have possibly finished this lab.
I’d also like to thank all my classmates in the period 4 class of Dr. Pike’s Physics 15 IB class for their patience and help.




References
Cannon. (2009). Retrieved March 31, 2009 from the Internet: http://en.wikipedia.org/wiki/Cannon
Cutnell, J.D. & Johnson, K.W. (2001). Cutnell & Johnson Physics. New York, NY: John Wiley & Sons, Inc.
Gao, C. & Gao, S. (2004). Math 3. Beijing, China: People’s Education Press.
History of cannon. (2009). Retrieved March 31, 2009 from the Internet: http://en.wikipedia.org/wiki/History_of_cannon
Hooke’s Law. (2009). Retrieved March 27, 2009 from the Internet: http://en.wikipedia.org/wiki/Hooke%27s_Law
Ideal Gas Law. (2009). Retrieved March 27, 2009 from the Internet: http://en.wikipedia.org/wiki/Ideal_gas_law
Impulse. (2009). Retrieved March 27, 2009 from the Internet: http://en.

dongma

上面是最近的物理实验报告。作为妈妈已经无法指导了。我是文科的。

huluzhu

看来就得早过去哈

ZHOUZHIQING

晕