Friday, October 31, 2014

This Blog's History: Does it Sink or Float?

This Friday in This Blog's History I bring back to you a simple science experiment I did with my daughters this past summer.  We took a jar of water and started taking random food items to see what floats and what sinks. 

There's nothing complicated about this experiment, but ask your kids what they think and why before you test out the food item.  The thought process that goes into the prediction is the science.  If one is right, awesome!  If not, why not?  What was learned?  

Thursday, October 30, 2014

The Rotting Apple Experiment

My daughters and I recently set up an experiment to see how different substances can affect the rate at which an apple slice rots.  We cut up an apple into several slices, placed a single slice in several canning jars, and then placed a small amount of a substance in each jar.  We then closed the lids and will closely monitor how quickly each slice rots.  Here's what we have in each jar.

Jar 1 - Nothing.  This is our control jar to see how an apple slice rots from air alone.

Jar 2 - Water.

Jar 3 - Salt.  Salt absorbs moisture.

Jar 4 - Baking Soda.

Jar 5 - Brown Sugar.

Jar 6 - White Sugar.  Is there a difference between white and brown sugar and its affect on an apple slice?  We shall find out.

These apples will definitely be harmed in this experiment, but in the process we will learn something!  :-)

Wednesday, October 29, 2014

October 23, 2014 Partial Solar Eclipse Recap

Last week I pointed out an upcoming partial solar eclipse on October 23, 2014.  I set up a telescope on top of a nearby parking garage, as seen below.

It was still clear enough out at the time to see a huge cluster of sunspots which was very cool!  However, a few minutes later the clouds rolled in and never cleared leaving me and about 40 students out of luck.  Bummer.  Oh well, I'll try again in 3 years when the next solar eclipse in the continental U.S. makes an appearance.

Tuesday, October 28, 2014

Starting a Fungus Garden

My daughters and I decided to start our own simple fungus garden.  'Fungus' and 'garden' in the same sentence equals one cool science experiment!  We've just started the experiment, so I won't have results to show for another week or two, but here's how you start the garden.

Begin with a large, clear plastic or glass jar.  Then toss in a few different food items, such as bread, fruit, cheese, lunch meat, cookies, chocolates, etc.  Whatever you want to toss in is fine.  Then spread a couple of teaspoons of water in the jar for added moisture.  Seal the jar with a lid and you've started a fungus garden.  Ours is shown in the picture below.

Each day over the next two weeks we'll closely examine the contents of the jar to determine which have mold growing first and how quickly.  Honestly, I don't know what to expect, so I'm just as interested as my girls are.  We should have result pictures to post in a week or two.  

Monday, October 27, 2014

What is Fog?

We've had several foggy days this fall in our neighborhood, which led my 7 year to ask me, while waiting for the bus one foggy morning, what is fog?  Is it a cloud?  Is it something else?  What is it?

We've all seen fog come and go, but what is it?  How does it occur?  Fog is nothing more than a collection of water droplets and/or ice crystals.  It's basically the same thing as a misty day, except the visibility is much worse in fog than it is when it is misting.  This makes it the same as a cloud, but on the ground.  That begs the next question.  How does a cloud form on the ground?  

Fog forms when water vapor near the ground cools and condenses (changes phase) from a gas to a liquid, hence the tiny water droplets.  How this happens can differ depending on the type of fog.  A great source for this is:

In most cases, the fog will "burn" off as the sun rises.  The temperature of the water droplets increase and change phase back into a gas.  

Friday, October 24, 2014

This Friday in This Blog's History: Mixing Water and Pepper

This Friday in This Blog's History I bring back to you a cool science experiment my daughters and I completed last month.  What happens when you mix pepper and water?  The results may surprise you!

Mixing Pepper and Water

Thursday, October 23, 2014

Drinking Through Straw

We've all drank through a straw before, but how does drinking through a straw work?  Are you sucking up the water?  Not really.  What happens when you suck on a straw is that you remove the air in the tube.  The atmosphere pushing on the liquid in the glass at all times.  When the air from the straw is removed, the air pressure on the water is greater than the air pressure in the straw.  Therefore, the air pushes water in the glass up the straw.

Physics tells us there's a limit to the height of a working straw.  Construct a straw several meters in length and you'll find it impossible to suck water out of it.  Why?  The force of gravity acting to pull the water back down the straw increases as more water is pushed up the straw.  When the downward force of gravity equals the force pushing the water upward, water can no longer be forced up the straw.  Make a straw too long, and it doesn't work.

My daughters and I set out to simulate this by using a regular straw.  We took a jar of water with a lid, poked a hole in the lid, slid a straw through the hole, then sealed the hole with play-doh.

Sealing the hole with play-doh prevents outside air from entering the jar.  The only air pushing the water up the straw is the air inside the jar.  The task is to try to suck up a mouthful of water.  At first a little water comes up the straw, but if the hole is sealed, that's it.  There's not enough air pressure inside the jar to continue pushing water up the straw.  Cool you get to use play-doh!!!

Wednesday, October 22, 2014

Ebola Statistics

The news cycle is currently focused on Ebola, and if you haven't noticed, then you really need to pay attention to the world around you.  :-)  It's important, however, to put Ebola in perspective.  Yes, Ebola is a very deadly virus and we should not underestimate the importance of controlling its spread.  At the same time, however, we need to make sure that we aren't exaggerating the possible spread of Ebola.  Right now Ebola is about the only thing the news and politicians alike are discussing.  There's even a politician saying that anyone found with Ebola should be "humanely executed."  Wow...just a tad bid overboard I'd say.

Now that may be a very extreme comment, but many politicians are asking for travel bans from West Africa to the U.S.  Let's look at the statistics and let's begin with a humorous look at the statistics.  You may have seen the following image trending on Facebook.

Yes, it is a silly comparison, but also a true comparison.  Kim Kardashian is only 34 years old and been married 3 times.  Ebola has killed exactly 0 people who contracted it while in the United States.  At the time I write this, 3 people have officially contracted Ebola within the U.S. borders.  The first, a nurse in Texas, is in good condition and appears to be on the path for a complete recovery.  This doesn't mean that no one who contracts Ebola in the United States will die or that there won't be more cases.  Personally, I doubt we will see a number greater than 10 for number of Ebola cases contracted within the U.S.  

Again, we should not underestimate the threat of Ebola and we should put every REASONABLE measure in place to prevent the spread.  I wish that U.S. citizens would take other common viruses just as seriously.  Take a look at the graph below.

In this graph the 1 Ebola death comes from the patient first diagnosed in the U.S., but contracted it while in West Africa.  Take a look at the flu deaths over the same 9 day period?  WOW!  Why are people not as worried about the flu as they are of Ebola?  Yes, if one contracts Ebola, that person is much more likely to die than a person who contracts the flu.  The flu, however, is an airborne virus that is much easier to spread from person to person than the bodily fluid-borne Ebola virus.

If you are scared of contracting and dying from Ebola, then I must assume you are 1,110 times more scared of dying from the flu virus.  No?  Based on death statistics, you should be.

My point is that yes, we need to be serious about Ebola, but we need to be just as serious about other diseases.  Ebola is simply NOT something to be worried about.

For a more detailed description of Ebola, check out the Mayo Clinic.

For more information on the number of Ebola cases in the U.S., check out the following link from the CDC.

Tuesday, October 21, 2014

October 23, 2014 Partial Solar Eclipse

If you enjoyed the total lunar eclipse on October 8, 2014, then you will definitely enjoy the partial solar eclipse that will take place on October 23, 2014.  A solar eclipse occurs when the Moon positions itself in a direct line between the Sun and the Earth.  The Moon is a much smaller object than the Earth, so total solar eclipses are very rare.  When one occurs, you have to be at a very specific location on the Earth.  See the map of past and upcoming paths of solar eclipse totality.

If you're outside the paths shown above, you'll still see a partial solar eclipse as long as you aren't too far from the path of totality.  More often, totality is never reached and one can only see a partial solar eclipse.  That's the case with the October 23 solar eclipse.  If you live in North America, you'll have a chance to see the eclipse.  Using a telescope with a solar filter, or proper glasses, you'll see the Moon blocking part of the Sun's disk.  The following site provides help on how to safely view a solar eclipse.

For more details and exact start/end times of the October 23, 2014 eclipse, visit the following website:

This is another great observing opportunity for you and your kids and it takes place during normal awake hours!  Don't miss out!

Monday, October 20, 2014

Egg Drop Results - Historical

Readers of this blog know that I've done the egg drop experiment several times with my high school students.  We just finished the project again this Fall.  I started the project during the Fall 2007 term and have continued it each year in my high school physics classes.  My students did a great job this fall and being the geek that I am, I dug through all of my notebooks and tabulated the results to determine survival rates of dropping from specific heights.  I left out the Fall 2007 term in my results since that group of students had a full sized grocery bag to use which made the project a bit too easy.  The table below shows survival rates for 102 ships starting with the Fall 2008 term and ending with the 2014 term.

2 feet survival rate = 100%
6 feet survival rate = 94.12%
2nd floor survival rate = 72.55%
3rd floor survival rate = 50.00%
4th floor survival rate = 34.31%
4th floor (rocks) survival rate = 12.75%
4th floor (rocks, upside down) survival rates = 5.88% (5 ships all time)
4th floor (rocks, thrown downward) survival rates = 2.94% (3 ships all time)
4th floor (rocks, thrown upward) survival rates = 1.96% (2 ships all time)
4th floor (rocks, thrown outward) survival rates = 1.96% (2 ships all time)
This year's winner is one of the 2 ships all time that survived everything we could do to it!  It finally broke when I removed a few pieces!!!  Here's what it looked like, minus the sandwhich bag I removed.

A big congratulations to these two students!

Friday, October 17, 2014

This Friday in This Blog's History: Removing Salt from Salt Water

This Friday I bring back to you a very cool experiment involving salt water.  Drinking salt water is not healthy for your body due to the salt content.  Therefore, before drinking it, one needs to remove the salt.  This post shows one method to remove the salt from salt water.

Removing Salt from Salt Water

Thursday, October 16, 2014

Making Clear Ice Cubes

Have you ever tried to make clear ice cubes?  No?  Then check out any ice cubes in your freezer.  Try freezing a class of tap water.  You'll find that finding and/or making clear ice cubes is very difficult.  Although you don't see them, water out of the tap contains small air bubbles.  As the water changes phase into ice, the bubbles expand and give the ice cube a cloudy appearance, as shown in the "cloudy" ice cube from my own freezer.

You probably don't have a need of making clear ice cubes, but it is possible to do.  Begin by boiling a pot of water.  The boiling process removes air bubbles in the water.  After boiling the water, very slowly poor the water into a freezer safe container.  It's important to pour the water very slowly along the side of the container.  Pouring too quickly or jostling the container will re-introduce air into the water.  Seal the container and place it in the freezer for a few hours.  Once the water has frozen, you should see a more clear ice cube.

Although not perfect, the picture above is our attempt to make a clear ice cube.  The container on the right is standard tap water.  The container on the left is frozen water after the boiling process.  The picture doesn't do this experiment justice, but the ice on the left is more clear than the standard tap water ice on the right.

Give it a try!

Wednesday, October 15, 2014

Updated Blog Stats

Because I like statistics I've continued to plot the progress of page views on this blog.  I'm happy to report that page views continue to increase as each month goes by.  Below is the latest chart showing the average daily views for each month starting May 2012 and ending with September 2014.

Aside from a couple of peak months followed by declines, the general trend is upward, with nearly 200 page views per day last month.  Hopefully soon I'll see this blog consistently crack 200 page view per month.  Getting close!

Tuesday, October 14, 2014

Balanced Fork Experiment

Here's a very cool science experiment my two daughters and I tested out the other day.  It's a classic center of mass experiment where you balance something that appears to be impossible to balance. We began by intertwining two forks and jamming a toothpick between them, as shown below.  Then it's a matter of placing the toothpick/fork on the edge of any glass.  It may take a moment or two, but you should be able to balance it.  It is very cool looking, as seen below!

Why does it balance?  It's all about center of mass.  If an equal amount of mass is on each side of the balance point, the object will balance.  If not, the object topples over.  Because the forks curve around the sides of the glass, the fork/toothpick combo remains balanced.  To make the experiment even more impressive, light the toothpick on fire and watch it burn all the way to the glass edge.  It will still remain balanced!  See our video below.  Very cool!


And here are the final pictures.  

Give it a try!  This experiment is sure to wow your kids!

Monday, October 13, 2014

The Pop Can Race

My 7 year old has been checking out science experiment books from her school's library which has given us several ideas for testing out different concepts in science.  Recently, one science experiment struck me as odd, and well...simply wrong!  The idea of the experiment is very simple.  Take a full pop can and an empty pop can of the same size, start them at the top of a ramp, and release at the same time.  Which reaches the bottom first?

Galileo showed that all objects accelerate at the same rate regardless of size/shape/mass, in the absence of friction.  Without air, a golf ball and a feather, when dropped at the same time will reach the ground at the same time.  This has been shown in vacuum tubes when the air is pumped out.  In real life situations, friction always plays a role.  The science experiment book stated that the empty pop can will always reach the bottom of a ramp first because there's less friction acting on it.

This immediately struck me as incorrect because friction isn't the only force in play.  Granted, the force of friction between the can and the ramp is probably greater for the full can.  I'm not denying that but air friction probably plays a bigger role on the lighter can.  I don't know for sure, I'm just suspecting this.  However, my concern here isn't friction.  My concern is the rotation of the can.  Rotating objects are a bit more complicated.  If the mass is distributed in different ways, the inertia of the object differs.  An empty can, with all of the mass on the outside, has a greater moment of inertia than the full can.  As a result, the empty can takes a bit longer to start its motion.

This is a common physics topic in my high school classes and there are several demos I show with rings and solid cylinders to hammer this point home.  The solid cylinders always beat the rings in a race down the ramp.

My daughters and I decided to test this out ourselves and sure enough, the full pop can ALWAYS reaches the bottom of the ramp first.  The book is simply wrong on this.  See our video below.


Later we raised and lowered the ramp and the full pop can still ALWAYS wins!  As you can tell from the video, my 4 year old was quite excited!  LOL!  Try it yourself.  If your kids get as excited as mine were in the video, then you've killed a good 30 minutes of time on a rainy or too hot day!

Friday, October 10, 2014

This Friday in This Blog's History: Does the Moon Rotate?

This Friday in This Blog's History I bring back to you a very common misconception regarding the Moon.  The same face of the Moon always faces Earth.  Because of this, many people think the Moon does NOT rotate, but in fact, it does.  The fact that only one side of the Moon faces Earth tells us that the Moon MUST rotate on its own axis.  For full details, check out the original post below.

Does the Moon Rotate?

Thursday, October 9, 2014

150 Science Experiments

My 7 year old is big into science experiments lately.  After returning her Science Rocks! book from her school's library, she came home that same day with another science experiment book, titled 150 Science Experiments.  The best part was her excitement after getting off the bus.  It was the first thing she wanted to talk about!

Granted, we've done a number of these experiments already, but we found a few we haven't done and added them to the to-do list of science experiments.  I encourage you to find this book at your local library.  It's also available on Amazon.

150 Science Experiments

It's a great book for a weekend of science experiments, although it's important to plan ahead and pick up needed supplies.

Wednesday, October 8, 2014

Lunar Eclipse Pictures

This morning's lunar eclipse, which is still in progress, was awesome.  My kids normally get up around this time to get ready for school, but I woke them up 15 minutes early to check out the eclipse.  AWESOME!!!  We caught the end of the partial eclipse and watched until totality hit.  Here are the pictures I took.

Look closely in that last one.  The Moon is there!

Tuesday, October 7, 2014

The Imploding Pop Can

Here's an awesome science experiment you can do with your kids that only takes a few minutes yet produces an amazing result!  See the video below.


The goal is to get an empty pop can to implode (crush in on itself).  To do so, take a pop can and empty the contents.  Place a tablespoon of water in the bottom of the can and place the can directly on a stove burner.  Let the can sit on the burner until you start to see steam coming out the top.  Let it sit for another minute.  Now take a pair of tongs and quickly, but carefully, use the tongs to pick up the can, tip it upside down, and submerge the can open side down into a large bowl of ice water.  The can will immediately implode making a loud noise in the process!

The video above is our attempt at this experiment.  It worked great and I assure you I didn't crush the can with the tongs!  It happened so quickly that I didn't get the phone over in time to capture the video of the crush itself.  I'll have to do better next time.  

So what's happening?  The can and air inside the can is very hot.  By submerging the can in the ice cold water open side down, the air inside the can can't escape.  Due to the drastic change in temperature from hot to cold, however, the air inside changes density very quickly and the can caves in on the sides.  Cold air takes up less space than warm air.  

If you still don't believe my video then I challenge you to try it out for yourself.  Very cool!

Monday, October 6, 2014

October 8, 2014 Lunar Eclipse

There's a great astronomical viewing opportunity coming up if you live in Asia, Australia, North America, or South America.  On the morning of October 8, 2014, there is a total lunar eclipse.  Although not all that rare, it can be anywhere from 6 months to 2 years between total lunar eclipses at a given location.

A lunar eclipse occurs when the Earth moves in a direct line between the Sun and the Moon.  The Earth blocks light from reaching the surface of the Moon and casts a shadow on the Moon.  During the total part of the eclipse, the Moon will appear reddish due to red light refracting through the Earth's atmosphere and reaching the surface of the Moon.

The exact time of the eclipse will vary depending on your location.  A great source to check the times for your location is:

October 8, 2014 Total Lunar Eclipse

This is a great opportunity for you and your kids to observe the skies together!  Take advantage of it!

Friday, October 3, 2014

This Blog's History: Popping a Balloon (Or Not)

This Friday in This Blog's History I bring back to you a cool experiment to break the surface of a balloon yet not pop the balloon.  You can do this through several different methods.

Popping a Balloon (Or Not)

Thursday, October 2, 2014

All-Natural Foods and Science

Here's another post on my continuing series on food and science.  Today the focus is on all-natural foods.  It's becoming more common for food manufacturers to place an "all-natural" label on their products.  But what does "all-natural" really mean?  Unfortunately not all that much.

The assumption, and the message that food manufacturers are trying to send is that all-natural foods are better for you.  That's not necessarily true.  All-natural means nothing when it comes to the quality or safety of the food you consume.  Supposedly these products or ingredients in products are naturally produced on Earth and therefore better for you.  Some of these products may indeed be good for your health.  Upon closer inspection, however, many "all-natural" substances found on Earth are deadly to humans.

Which ones are deadly?  Well, for starters, arsenic.  Arsenic is naturally produced on Earth and is an "all-natural" substance.  As little as 70 mg of arsenic in drinking water can kill you.  Another "all-natural" substance is carbon monoxide.  Breathing it in is deadly and we have CO detectors in our home to alert us of high, dangerous, levels.  Take water itself.  Water is "all-natural", but if one drinks too much of it too fast, it is deadly.  Your bodily organs begin to shut down.

Claiming that something is "all-natural" is pointless.  It doesn't mean anything and it certainly doesn't mean the food product is healthy for your body.  Both salt and sugar are "all-natural" but eating "all-natural" food products that contain a lot of salt and sugar is most definitely not healthy for your body.  In addition, an "all-natural" food product may not be 100% "all-natural".  From the FDA:

"From a food science perspective, it is difficult to define a food product that is 'natural' because the food has probably been processed and is no longer the product of the earth. That said, FDA has not developed a definition for use of the term natural or its derivatives. However, the agency has not objected to the use of the term if the food does not contain added color, artificial flavors, or synthetic substances."

Eating healthy is simple in theory, although I'll admit much harder in practice.  Eat plenty of fruits and vegetables, limited amounts of red meat, and keep sugar and salt to minimum levels.  That's it.  Buying products labeled "all-natural" simply for the reason of them being "all-natural" is a waste of money and may provide no health benefit at all.

Wednesday, October 1, 2014

Climate Change and Global Warming Science

Depending on the age of your children you may find them asking questions about global warming and climate change.  It's in the news all the time, although often due to climate change deniers that dominate the airwaves.  Climate change is not a simple topic and can be hard to understand without a strong science background.  Heck, even with a strong science background, there are aspects of climate change that are not easy for me to understand.  Fortunately there are many sources out there to help you understand the truth of climate change.  Here's a great video that tackles 13 of the common myths that climate change deniers push.

13 Misconceptions About Global Warming

To put it bluntly, there is no longer any scientific debate as to whether the Earth is warming.  It is, and it is very clear from the data.  To be a climate change denier is to ignore the world around you and live in a world of ignorance.  The question and debate now revolves around the question of what we should do, can do, and how long we have to solve the problem.

If your kids are asking you about climate change and you don't have an answer, sit down with them and take a look at this video.  Work to understand the issue together.  Telling your kids that climate change isn't happening and scientists are lying to the public is the same as telling your kids that science isn't important and plays no role in their lives.  Don't do that.  Don't turn your kids away from science.  Be a responsible parent by teaching them the importance of investigating and researching answers to their questions.