Pond Ice

A couple of weeks ago my wife and I took our daughters on a walk through the neighborhood.  It had been cold enough the previous few days that a few nearby ponds had frozen over.  On the day of the walk, however, the temperature outside was close to 50 degrees F.  The ice on the ponds was quickly melting, but had not finished melting yet.  We had fun throwing rocks onto the ice to see if we could break through.  We did.  We then found a couple of large sticks and starting poking the ice near the pond edges.  The cool thing is that the ice was the perfect thickness to break, but not shatter the ice into tiny pieces.  This allowed us to take out chunks of the ice from the pond.

We then threw these chunks out onto the pond ice and watched it shatter into tiny pieces.  The next cool thing we found is that some of the shattered pieces flew far distances across the pond ice.  Why?  The answer is conservation of momentum.  The large chunk of ice has some momentum when thrown.  Momentum must be conserved, disregarding friction, meaning the momentum of each tiny piece must add up to the momentum of the original big chunk.  Some of the shattered pieces moved back toward us while others barely moved at all.  To account for these zero and negative momentum pieces, there must be several pieces with large positive momentums.  These are the pieces propelled forward and travel great distances across the ice.

In the end we had a great time at the ponds.  I felt like a kid again as I cut out pieces of pond ice and threw them across the pond.  Neither of our daughters wanted to leave!  They were having a great time as well.  Fun times!

Top Ten Most Viewed Posts

I started this blog approximately 2.5 years ago in May 2012.  In that time I've posted 737 times.  This is blog post #738.  Each month this blog receives about 4,000-6,000 visits.  Which posts are visited the most often?  Below I've linked to the top ten all time viewed posts and the number of views each has received.

1.  The Egg Drop Experiment - 8021 views

2.  Thunder/Lightning Misconception - 7092 views

3.  Can You Get a Moonburn? - 3214 views

4.  Volleyball - 2982 views

5.  What Direction Does the Sun Rise and Set? - 2887 views

6.  Trouble at the Dentist - 2699 views

7.  Sonic Boom - 1218 views

8.  Egg Drop Experiment - 1121 views

9.  Upper Peninsula Trip #6: Ticks - 832 views

10.  Rosetta/Philae Comet Landing Pictures - 790 views

If you haven't seen these posts before, check them out, others certainly have!

Pulling Apart Two Magazines - Paper Friction

How much friction is there people two pieces of paper?  Answer:  Not much.  You can easily test this by placing one piece of paper on top of another and then pull the two pieces apart horizontally against each other.  The two pieces easily slide apart.  But what if you add more pieces of paper?  A really cool experiment to test this can be done using two phone books or two magazines.  My daughters and I grabbed two magazines and started interweaving the pages together.  One page from one magazine on top of the other page, and continue until the two magazines are interwoven page by page.

Now have on person grab one magazine binder on one side and a second person grab the other binder on the other side.  Now pull horizontally.  Do the magazines come apart?  If you pull hard enough, yes, but you have to pull very hard.  The greater the number of pages, the harder it is to pull apart.  My daughters gave it a try and were unsuccessful as you can see in the video below.

We then picked up one magazine and held the bundle vertically to see if gravity could do the trick.  No luck.

The friction force between any two pages is small, but add it up over all of the pages and the force is very large.  Mythbusters did this once with two phone books and ropes and chains were breaking while the books stayed stuck together, simply from the friction force of paper on paper.  

Give it a try, your kids will find it very cool!

This Blog's History: Candle/Air Pressure Experiment

Can you make water "magically" rise up a glass/bowl?  Maybe not with your mind, but with science you can!  This is an experiment I originally discussed last month, but I'm bringing it back to you for This Friday in This Blog's History.  Check it out!  It's very cool!

Candle/Air Pressure Experiment

How Fast Must Santa Travel

Today is Christmas and along with Christmas comes Santa Claus.  Depending on the age of your kids, they may or may not still believe in Santa, but that's not the point of this post.  Each year on the first day of the second semester of my physics I give my students a thought problem where they have to calculate an approximate speed that Santa must travel to visit every house in the world in 24 hours (ignore time zone changes).  Let's work through it.

To start this problem I assume that Santa begins at the North Pole and slowly moves in circles about a given latitude toward the equator and then to the South Pole.  Let's also assume Santa has some magical powers and doesn't have to physical stop at each house.  He just flies through the air throwing presents left and right.  The presents magically work their way into the houses.  Let's also assume Santa has incredible arm strength and has a throwing reach of 500 meters in each direction.  Thus each swipe around the Earth covers a width of 1 km.

The circumference of the Earth is 40,075 km.  Santa makes circles going down one side of the Earth, so the distance Santa travels down the Earth is half this...20,037 km.  If each swipe has a width of 1 km, Santa must circle the Earth 20,037 times.  So how long is each of these swipes?  At the equator the swipe is 40,075 long, but at the North Pole the swipe is 0 km long.  Let's assume the average swipe is half the circumference of the Earth.  Thus we end up with:

20,037*20,037 = 401,491,387 km traveled.  Add on to that a one way trip back from the South Pole to the North pole and we get:

401,491,387 + 20,037 = 401,511,424 km traveled

Santa must do this in a 24 hour period.  To get Santa's speed we divide distance by time (converting to seconds):

401,511,424/86,400 = 4,647 km/s

That's blazing fast!  But is it physically possible?  The speed of light, the fastest anything with mass can travel is 300,000 km/s, so Santa is traveling less than this.  In our estimate, Santa travels at a speed of 1.5% the speed of light.  Well within the realm of possibility!

Too much geek for one day?  :-)

Sky & Telescope Magazine

If you haven't figured it out yet, I'll make it very clear now.  I'm a geek when it comes to science and I love reading science related books and magazines.  I subscribe to a few science magazines and every once in a while drop one and subscribe to another for a period of time.  I recently subscribed to Sky & Telescope.  The first issue arrived the other day and I immediately dug into it.  It's a great astronomy related magazine that explains things in a very general way without dumbing things down too much.  It can get a bit technical in articles that discuss amateur telescopes, but nothing you can't read through and get a basic idea of what's going on.  It's definitely a magazine I recommend for the science lover and anyone with a basic interest in astronomy.  Magazines are a great way to explore a field of science without getting over technical and confusing.

Straw Spray Experiment

I credit students in my high school physics class for introducing me to this science experiment/demonstration.  They sent me a link to this YouTube video, provided below, and asked me if I could get it to work, because they were unable to reproduce the experiment.  The idea is to fill a glass full of food colored water and tape a straw vertically inside the glass.  Then take another straw and blow perpendicularly at the very top of the taped straw.  The physics says that blowing air across the top of the vertical straw reduces the air pressure at the top of the straw, causing liquid inside the straw to rise.  As the liquid rises to the top, the air blowing horizontally causes the liquid to spray outward onto the wall.

Being The Cool Science Dad that I am, I had my two daughters help me out with this task.  We set it up just as described in the video and I started to blow through the straw.  The result?  Nothing.  Hmmm....as any good scientist does, we started to investigate why it wasn't working.  We tried various things and eventually cut the straw inside the glass as short as possible.  This reduces the height the liquid in the glass as to rise.

The result?  It worked, although you have to blow very hard into the straw.  I was barely able to get it to work, and my daughters had no luck at all, but it worked!

Try it out yourself!  Just be sure to have towels ready because you'll be blowing liquid out of the glass onto the wall/floor.  It's a cool science experiment because you see water appear to magically rise up the straw and out of the glass.  I say 'appear' because it's not magic.  It's science!

Dancing Pros and Physics

The other week my family and I had the opportunity to go see a Dancing Pros Live event.  If you're unfamiliar with Dancing Pros, check the link below.

Dancing Pros Live

The show is hosted by Alan Thicke and is composed of several top dancers that compete in a entertainment style competition.  I had no idea what to expect from the show, but I was very impressed.  Both of my daughters loved it!  My 4 year old fell asleep after intermission, but my 7 year old was just as amazed as I was at the moves these dancers could pull off.

There's a lot of physics that goes into dancing, much of it centered on balance.  Consider a person standing straight up.  At what point does one topple over?  If you lean over far enough, eventually your center of mass moves outside of your feet.  Everything else being equal, that's the point at which you will fall over.  The muscles in your body will help to avoid this, but eventually you will fall.

At the Dancing Pros Live event, we saw a male dancer do a hand stand, which is already a difficult feat.  Then, while on his hands, he slowly bent the bottom portion of his body over, stomach facing up, and keeping his feet straight out.  He reached a point where he was almost bent over at the waist at a 90 degree angle, and held it for a couple of seconds!!!  WOW!!!!  Simply wow!!!  The muscle strength and control needed to do that is simply amazing!  It looks physically impossible and is unless you have an extremely strong core.

Anyways, if you get a chance, take your kids to a Dancing Pros Live event.  They will love it!!!

This Blog's History: Seeing Your Own Breath

This Friday in This Blog's History I bring back to you a common misconception regarding your own breath.  Sometimes you see it coming out of your mouth or coming out of someone else's mouth.  Why?  Is it smoke?  Steam?  A cloud?  What's going on?  Check out the original post for the answer and for more details.

Seeing Your Own Breath

Black and White TV

The other weekend my wife, kids, and I actually had a full free day with nowhere to go!  That lasted a whole 30 minutes because I quickly learned I had a plumbing problem to fix that required a trip to the store.  That's a whole other story, however.  In the afternoon we popped a batch of popcorn and cuddled up on the couch together to watch a kids movie.  It was my 4 year old's turn to pick and she chose to watch a movie she picked out at the library earlier that week:  The Smurfs Holiday Celebration.

This is old school Smurfs that my wife and I watched in the 1980s when we were kids.  I was telling this to my 7 year old and she looks up at me and says "was that when it was in black and white?"  Really!?!?!?!  How old do you think I am?!??!?!  It was the 80s, not the 50s.  LOL!  Crazy things that kids say!

My 7 Year Old Teaches Science to my 4 Year Old

The other night at dinner my wife and I were making iced tea.  We heated up a container of water, placed the tea bags in, and sat it on the table.  While eating dinner, my 4 year old asks "Mommy, why is there smoke coming out of the tea?"  My 7 year old responds "that's not smoke, it's tiny water droplets."

It took me a moment to realize that she was teaching my 4 year old science.  She was absolutely right.  We think of steam as a gas, but it's not.  The iced tea is evaporating into the air, but as it evaporates into a gas, the gas cools and condenses back into tiny water droplets.  The water droplets take on a cloud, or in this case, smoke type of an appearance.

This was a proud science Daddy moment!

Correct Guess

My two daughters recently entered a contest at our local library to win a set of kids magazines geared toward their age.  To win the set of magazines, they had to guess how many Legos were in a jar.  The entry with the closest guess wins the prize.  Some people may claim we cheated, but I disagree.  We simply used math skills to help us out.  I began by letting them know there was a method that would help us with our guess.  I told them that if we know how many Legos tall the jar is and how many Legos across the jar is, we could do a bit of math to get a close guess.  Here's how:

The jar was cylindrical and there's an equation for the volume of a cylinder.  The volume of a cylinder is given by:

V = Base Area*Height = pi*r^2*h

I told them to count the number of Legos high, and they each did.  Then I asked them to count the number of Legos across (diameter) and they both did.  We plugged the numbers in a calculator and they both had a number they wrote down and put in the guess box.  A week later after the contest had ended, I received a phone call letting me know that my 4 year old had the closest guess!  She was only 1 Lego off!!!

So who said knowing math doesn't come with perks?  Okay, perks for my 4 year old, but perks nonetheless!

Fiction Books Promoting Science

The other night my 4 year old picked out a couple of books to read before bed that had a science theme to them.

1.  Biggest, Fastest, Strongest

This book discusses a few of the "extreme" animals in the world in terms of their size and/or what they can do.  For example, what is the largest animal in the world?  Smallest?  Tallest?  Fastest?  The book does a great job introducing young children to these animals and has sizes to scale in the book, comparing the animal to a human.

2.  Magic School Bus Lost in the Solar System

Overall this book does a great job introducing kids to the Solar System through a fictional story.  Granted, it does a horrible job explaining the asteroid belt.  It gives the impression that the asteroid belt is loaded with asteroids that you must dodge to get through when in fact there are millions of miles between any two asteroids.  But if you can get through that part, it's a cool way to introduce kids to space.

There are plenty of other great books out there that introduce kids to aspects of science, but these were the two my 4 year old picked out last night.

This Blog's History: The Celery and Colored Water Experiment

This Friday in This Blog's History I bring to you once again the celery and colored water experiment.  It's a very simple experiment that requires celery, water, and food coloring.  That's it!  Check out the full details in the original post.

The Celery and Colored Water Experiment

Winter Science Experiments

With winter weather sweeping across much of the country, now is a great time to do a few winter science experiments with your kids.  Here are 2 that are easy to do and allow your child the opportunity to investigate and predict outcomes.

1.  Which freezes first?  Hot water or cold water?  Fill two same sized glasses with the same amount of water and place outside at exactly the same time.  Common sense might tell you that the cold water freezes first since it is already closer to the freezing point of water.  But is common sense correct?  What happens when you reduce the volume of water?  Half the water?  Quarter full?  Etc.?  Try out different volumes of water to see if it has any effect on which temperature of water freezes first.

2.  Place a full, non-opened can of pop outside and wait for it to freeze.  What happens?  Try different types of pop.  Does one can freeze more quickly than another?  Setup a video camera to see the freezing in action.  It may take awhile, so make sure your camera has plenty of memory.

We'll be trying out a few things at my house and I'll post results here when they come in.  The pop can freezing requires a video camera, because inevitably the freezing action happens when you're not looking!

Spring Break 2015 Vacation Opportunity

Looking for an awesome science filled spring break vacation for you and your kids?  A great option, although very expensive, is a solar eclipse cruise!  There's a total solar eclipse in March 2015 that will sweep through the northern Atlantic.  The eclipse time itself will only last for a few minutes, but there's a ton of great scenery and sight seeing options in this area.  There are several cruise linesnoffering a solar eclipse cruise.

Faroe Islands Solar Eclipse Cruise

Smyril Line Cruises

Cruise and Maritime Voyages

It's going to cost a family of 4 around $10,000 to do this trip, but what an amazing experience!!!  My wife and I briefly entertained this, but the timing with school and work is horrible and that's not really in our budget this year.

But if it works for you, go for it!!!

The S-E-X Picture Frame

The other day at lunch we're all sitting down at the table eating when my wife leans over and asks me, "why does that picture frame say sex on it?"  Um...I looked over and sure enough, there's the word sex.  The picture frame in question, seen below, is a frame the girls made on Halloween with some of their friends.  This particular frame was made by my 4 year old with, gulp, help from me!

My 4 year old was asking me to help her spell certain Halloween related words.  She started with boo, followed by ghost, then cow (because I was a cow for Halloween), and then moo.  I helped her pick out the letters and she stuck them to the frame.  Then I went off to get ready for trick or treating and she finished the frame with random letters.  Several weeks later we noticed that she spelled sex, with a backwards 'e'.  :-)  

Yep, some great parenting going on here.  :-)

Discover Magazine Top 2014 Science Stories

The January/February 2015 issue of Discover Magazine recently arrived at my house.  The major feature in this issue is a recap of the top 100 science stories of 2014.  Very cool!  I highly recommend grabbing a copy of this issue to increase your knowledge of science current events.  The issue is very informative.

I haven't read through the entire issue yet, but glancing through it, the number 1 story is Ebola and the number 2 story is climate change.  I have to say I disagree with this ranking.  Yes, Ebola was a big story, but the only reason it was a big story was due to the misinformation spread by the media and many politicians.  The Ebola story is definitely worthy of top 100 status and should be ranked quite high given the outbreak in Africa.  Remember, however, no one who contracted Ebola in the U.S. died and only two people contracted Ebola in the U.S.  The others treated in the U.S. were treated AFTER they contracted it in Africa.  

To me, climate change is far more important of a story than Ebola.  Climate change affects the entire globe, all 7 billion plus people.  That's my opinion.  Regardless, this is an issue you should definitely check out!

This Blog's History: The Purpose of a Lightning Rod

We've all seen lightning rods, but what do they do?  Not what you think!  I previously discussed this on this blog several months ago, so for This Friday in This Blog's History I bring back to you the original post on lightning rods.

The Purpose of a Lightning Rod

Does Eating Turkey Make You Sleepy?

It's now a week after Thanksgiving, a holiday that usually involves much over-eating and sleeping on the couch.  What causes the sleepiness after a Thanksgiving meal?  We often hear that turkey is the culprit, but is it really the turkey that causes you to fall asleep after Thanksgiving dinner?  Let's see what the science says.

The saying goes that the amino acid L-Tryptophan, which turkey contains, causes sleepiness.  WebMD describes it better than I can:

"Tryptophan is needed for the body to produce serotonin. Serotonin is used to make melatonin, a hormone that helps to control your sleep and wake cycles."

There you go, turkey causes sleepiness, right?  Not so fast.  The amount of L-Tryptophan contained in turkey is similar to that found in most other poultry products.  Therefore, one should find themselves just as sleepy after eating chicken.  Yet we never associate eating chicken with sleepiness. So what is really going on?

The real culprit isn't the turkey itself, but all of the other food that goes along with it at Thanksgiving.  Potatoes, stuffing, corn, yams, pie, etc.  Most of us tend to overeat at the Thanksgiving meal because there is so much delicious looking food right in front of us.  After overeating the digestion process requires more energy.  It is this excess in used energy that induces sleepiness after the Thanksgiving meal!

So next Thanksgiving, don't blame the turkey, blame yourself for eating too much food.  :-)

For more information, check out the WebMD explanation of turkey and sleepiness.

The Truth About Tryptophan

Holiday Gifts For My 4 Year Old

Earlier this week I published a post on science-related gifts for my 7 year old this holiday season.  While shopping for gifts, my wife and I were looking into science-related gifts for my 4 year old as well.  She's not quite at the age where she's as interested in science directly as my 7 year old, but she is interested in several things that develop skills directly related to science.  For example, we usually get her a Lego set of some kind for gifts.  She loves putting them together.  We help her follow the instructions to start, but then she takes them apart and starts building her own creations.  Legos are a tool for her to use her imagination and investigate several scenarios on her own.  That's science!

This holiday season we're giving her a couple of Lego items as gifts, but we are also getting her a GoldieBlox item.  GoldieBlox is a company whose self-described goal is "to get girls building."  Consider it a mix of Legos and Tinker Toys.

For more information, checkout out the GoldieBlox website.

Just as I encouraged you earlier this week, I encourage you again to give a few science related gifts this holiday season.  Provide kids with science opportunities and they will love it and grow to love science as an adult.

Underwear Bears

This is what my wife and I found in the living room the other day.

Yes, those are two stuffed bears dressed in my 4 year old's pajamas.  What's that on their heads?  Yes, each bear has a pair of my 4 year old's underwear wrapped over the head as a bandanna.  Why?  Don't ask!  I have a Ph.D. in astrophysics and I'm clueless!!!  :-)

Holiday Gifts For My 7 Year Old

Over the Thanksgiving holiday my wife and I did all of our holiday gift shopping...without leaving the house.  We both sat at the kitchen table, each with a laptop, and started searching and discussing what to get.  My 7 year old is very into science.  She's always bringing science books home from her school's library, and just discovered the science section at the local public library.  In addition, she's always talking about science experiments and coming up with her own.  My wife and I had a few gift ideas for her this holiday season, but I wanted to add something related to science to her list, knowing that she would love it.  We decided on two science items to include in her gifts this year.

1.  An Edible Chemistry Set - This set comes with materials for 15-20 science experiments that produce something edible.  I'm preparing myself to help her with a few the day she opens the gift.  I know she will be super excited about it!

2.  A Microscope - Not an expensive one, but one that she can get her hands on and investigate things on her own.

I know my 7 year old well enough that her eyes will light up when she sees these two science gifts.  At the moment I'm not sure who's more excited, me or her!

I encourage anyone reading this to include a science item or two in your gifts to your children, cousins, nieces, nephews, brothers, sisters, etc.  Expose young children to science and they will grow to love science as an adult.