|
Krampf #467 Towels
|
KRA-@aol.com
|
Oct 04, 2006 07:49 PDT
|
Robert Krampf's Experiment of the Week
<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
This Week's Experiment - #467 Towels
Greetings from the Lion Country Safari campground in West Palm Beach, FL. I
am doing shows for Florida Power and Light this week, and it is fun staying
at the campground where the lions roar every morning.
Before we get to the experiment, let me apologize for the weeks that I have
missed sending out an experiment. Recently, my life has been very hectic and
exciting. The first DVD for the FCAT science series is finished, and we are
working on the next one. In addition to that, was my 50th birthday trip to
Death Valley and Sequoia National Park. Then two weeks ago, I made another,
very special trip to Talullah Falls, Georgia for a private wedding ceremony.
Nancy Wilson, a long time friend, is now Nancy Krampf, my wife. She enjoys
adventures as much as I do, and we should have all sorts of fun, new
discoveries to share with you.
The idea for this week's experiment came from a water leak. We woke up to a
lot of water and wet floors. The clean up gave me plenty of time to think
about how a towel works, and why it soaks up water. To explore this, you will
need:
a glass of water or your favorite drink
2 soda straws
Thin straw or coffee stirrer
a paper towel
Fill the glass with some tasty liquid and put one of the straws into it.
Before you take a drink, look closely at the straw. Even if the straw is not
clear, you should be able to see that the liquid has risen slightly up into the
straw.
This is called capillary action. Water is very sticky stuff. When it
comes in contact with the straw, the water molecules stick to the plastic. They
are attracted so strongly that the water climbs slightly up the surface. How
high the water will climb is controlled by several things.
First, it is controlled by the material. There are some substances, such as
oil and wax, that water does not stick to, so the water will not climb up
their surface. A towel made of wax would not work very well.
Second, to do much climbing, the water needs a small space. Notice that the
water climbs the inside of the straw, but does not go nearly as high on the
outside. Is the outside of the straw made of something different? No. Put
the second straw into the glass, beside the first straw. Place the straws
side by side, and then move them very slightly apart. You should see that the
water has now climbed up between the two straws. Why?
On the outside of the straw, the water is only sticking on one side, the side
towards the straw. All the water on the side away from the straw is being
held up by the attraction on the other side. The water will climb until the
attraction of the water to the plastic is balanced by the downwards pull of
gravity. With the two straws, you have water sticking to the plastic on two
sides. Twice as much support holds up twice as much weight, which lets the
water climb higher. Inside the straw, the water is surrounded, sticking on all
sides, so it climbs even higher.
Is there a way to make the water climb even higher? Yes. You could make
the straw smaller. If you can find a very thin straw, or one of the
straw-like coffee stirrers that they give at fast food places, compare a thin straw
with a thick one. You will see that the thinner the straw is, the higher the
water will rise. Why does the water climb higher in a thin straw? The water
in the center is being supported by sticking to the water that is sticking to
the plastic. A smaller straw means that there is less water in the middle to
be supported, so the water can climb higher.
So for a towel to work well, it needs to be made from a substance that water
sticks to very well. It also needs to have lots of tiny spaces for the water
to climb into. The fibers in the threads of the towel serve that purpose.
Now, think back to the straws. Which do you think would support more water,
one large straw or two small ones? Right. Two small straws would have
more surface area for the water to stick to, so they would support more water.
A towel that has many, very thin threads would work better than one with
fewer, thicker threads. That is the idea behind the new, microfiber towels.
Lots of very small fibers work very well at soaking up lots of water.
Now, you can finish your drink and think about how towels work, without the
need for a major water leak to get you started.
Have a wonder filled week.
****************************************
This weekly e-mail list is free from charge. You are welcome to forward it
to friends, print it in your newsletter, repost it on the Internet, etc., as
long as you do not charge for them and my name and e-mail address are
included.
Please forward this e-mail to anyone that you think might enjoy it.
To join the list, send a blank e-mail to: krampf-s-@topica.com
on-line archives are located at:
http://groups.yahoo.com/group/krampf/messages
http://www.topica.com/lists/krampf/read
***************************
Robert Krampf's on-the-road schedule:
My calendar is now on-line. You can see a detailed calendar, with dates,
times, schools, etc. at http://www.krampf.com/m_tour.html
***************************
Check out my web site at:
http://www.krampf.com
From Robert Krampf's Science Education Company
PO Box 60982
Jacksonville, FL 32236-0982
904-388-6381
|
|
 |
|
