Bernard Nebel
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Sorry to be so long getting back to you.
After researching your question on the internet, I have concluded that my description in the text falls short.
First, it can easily be demonstrated that vegetable oil is actively absorbed by a paper towel. Roll a piece of paper towel into a stick-shape and place it in a glass with bit of vegetable oil in the bottom. Over the next couple hours it will be seen that the the oil does wick up the paper towel one to two inches. Therefore, without doubt, oil on paper towel dose exhibit capillary action, but it is slower and not as “strong”. The oil will not rise as far on paper towel as does water.
It turns out that capillary action does not depend on hydrogen bonding. It only depends on the paper or other wick material not repelling the oil. (If the paper repelled the oil we would see the oil remaining in droplets on the paper surface.) Once the oil penetrates the tiny spaces among paper cellulose molecules, capillary action comes into play and here is the main point.
Capillary action only depends on the liquid molecules having a greater attraction to the solid (paper) surface than they do for each other. In other words, the oil molecules have a greater attraction to the cellulose molecules of the paper than they have for each other. It is this difference that facilitates capillary action, not hydrogen bonding by itself. With hydrogen boning the difference is great; hence very marked capillary action with water. With oil, the difference is very slight but is still there. Hence the oil does exhibit capillary action, albeit weakly.
I hope this helps, Emily. Thank you for your interest and questioning. It has gotten me learning something new myself.
Thank you for your question Emily. It baffled me too. I pulled the following off the internet. I hope it helps.
2. Cellulose and Polarity:
Cellulose, the main component of paper towels, is a polymer made of sugar molecules.
These sugar molecules have polar (charged) regions.
Oil molecules are generally non-polar.
However, paper towels can still absorb oil due to the capillary action and the ability of cellulose to create a network that can trap oil molecules.
The porous structure of the paper towel allows oil molecules to penetrate and be held within the towel.
3. Adhesion and Cohesion:
Water molecules are cohesive (they stick to each other) and adhesive (they stick to other materials, like cellulose).
While oil is not as strongly attracted to cellulose as water, it is still able to be absorbed through the capillary action and the physical structure of the paper towel.
The oil molecules are trapped within the spaces of the paper towel, effectively removing the oil from the surface it was on.There is a section labeled “Practices” right after “Time Required” in each lesson. It is subtitled, “Students who demonstrate understanding can:” Use this list as a way of quizzing your kid and focus on reviewing/teaching what they don’t know.
Sorry, I can’t offer anything myself. However, contact the Facebook group:
https://www.facebook.com/groups/308651699340117
They may be able to help.
Sorry, I can’t offer anything myself. However, contact the Facebook group:
https://www.facebook.com/groups/308651699340117
They may be able to help.
This depends entirely on his previous background. If his background spotty, it is best to start with vol. I to make sure he has the basic concepts presented there. Lesson can be covered quickly in an age-appropriate way. Also, please go to the BFSU Facebook group:
https://www.facebook.com/groups/308651699340117
BFSU users there will be helpful.Hello Rachael,
Your son has recognized a difficulty with defining everything as solid, liquid, or gas. Congratulations. Yes, there is a broad spectrum of “consistencies” between the most liquid and solid. It is a property known as viscosity. It is measured as the amount of time it takes the material to flow through a given opening, or the pressure needed to force it through.
There is a whole field of specialized science/product manufacturing dealing with how to give things the desired viscosity for a given use. Think of tooth past, skin lotion, engine oil, paint. An added complication is that viscosity of most things changes gradually or markedly with temperature. I left this out of the text to avoid the extra complication at the beginning level, but I am happy to see that your son recognized it.
Thank you for your question, Emily. It is both voltage and the current (amps) that are significant. Think of volts as pressure. First, there must be enough pressure (voltage) to push current through the body. Second, there must be enough current (amps) to do damage. “Danger, High Voltage” signs are to say that there is enough voltage to potentially cause current to leap from the power cables to your body and then then to ground. That there is enough current (amps) in the system to cause damage is taken as a given. I hope this helps, but please ask further.
Hello
You raise an interesting question. I swim but I am not a swimmer. I really hope that someone with more knowledge in this area will chime in.
Looking at the problem from an overall physics perspective, however, I question how much of role momentum (the tendency of a moving body to keep moving) actually plays. The greatest resistance to a swimmers forward movement is drag of the water — “friction.” This friction will tend to dominate the outcome, momentum notwithstanding.
Therefore, it seems to me, the focus should be on movements/motions that minimize this friction. That, and on movements/motions that maximize pushing forward. Again, I hope that someone with more knowledge will chime inIt depends on his background thus far. BFSU is designed to build understanding in logical systematic steps each building on what has gone before. If he has not had steps one and two, you cannot expect him to make much sense of step 3, even with help. I recommend starting with volume 1 then 2 and doing a review using the “Practices” section of each lesson. Only spend time on filling in ideas/concepts that he has missed or have fallen away. After this, you can be assured that he has the background or Volume 3.
Thank you for your question, Amy. Sorry to be so long in getting to it.
To start, please don’t make this more complex that it is. The key point of the lesson is to have kids observe that whatever biological tissue we look at, we find that it is comprised small units we call cells. Cells are too small to be seen with the naked eye. The images they are going to examine are made with aid a microscope.
Start with plant tissues where cells are most conspicuous. Google in turn:
Plant leaf cellular anatomy images
Plant root cellular anatomy images
Plant stem cellular anatomy imagesIgnore all technical terminology; species makes no difference at all. With each sort of image, draw your kids to focus on the individual units, cells. Have them follow/trace the outlines of cells and model how they are actually three-dimensional structures. They may be shaped like boxes, sausages, pancakes, or otherwise, but whatever their shape(s), they go together to make the particular part of the whole.
You may go on to observe the cellular structure of animal tissues in the same manner. Google in turn:
Skin cellular anatomy images
Muscle cellular anatomy images
________ (insert tissue/organ as your kids desire) cellular anatomy imagesYou might insert the discovery that all biological tissues are comprised of cells is one of the most profound breakthroughs in the history of biology. That discovery had to wait for the invention of the microscope.
The second part of the lesson.
After the discovery that every biological tissue examined is comprised of cells, the next question was: Where do those cells come from. Untold research and observation has revealed that only origin of a cell is from a pre-existing cell via a process of cell division. The key point is this. All growth and reproduction of biological organisms hinges on the division of one or more pre-existing cells. Following their formation via division, a cell may go on to grow and take on the size, shape, and function of the tissue in which it resides. Have kids observe a time laps video of cell division. You can ignore all technical terminology. The key point at this stage is that the origin of every cell in an organism is from another pre-existing cell.You and you kids undoubtedly have further questions. Please do not hesitate to post them. I will try to respond in a more timely manner.
Hi mastros, Sorry to be so long in answering your post. I think winter is a perfectly good time to start BFSU, and your beginning lessons will be the same. A/B-1, A-2, B-2, D-1, C-1, B-3, although the order may differ. As you get into spring you will probably want to continue heavier on the B-lessons as they fit into what kids are observing in the real world, but don’t totally neglect lessons in other areas. Please post your question on our Facebook site: https://www.facebook.com/groups/308651699340117 I am sure you will get more detailed responses from folks who have been through it. Thanks for asking.
