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The World’s Safest Potato Launcher

This is just one of the amazing articles in Homeschool.com’s virtual magazine – Summer Fun

 

Let me show you how easy it is to take a few simple items and turn them into a fun and educational toy that is easy and safe enough to perform by any child.

The materials you will need to create this potato launcher are very simple:

  • Three feet (~1 meter) of 3/4″ (1.9cm) PVC pipe
  • Several large potatoes
  • Sandpaper (medium-coarse grain)
  • 2-3 feet (0.6-0.9m) wooden dowel rod with a ½” diameter (1.3cm)
  • Safety goggles

Complete the following procedure to construct your potato launcher:

1)      Use the sandpaper to grind the inner walls of the PVC pipe at both ends to a mild edge.

2)      Put on your goggles and head outside!

3)      Place a potato on the ground and stab it with one end of the PVC pipe so a plug is created in the tube.  Repeat this on the other end of the pipe.

4)      Hold the launcher in one hand and the wooden dowel in the other.  Aim the launcher towards an open area and never in the direction of a person.

5)      Use the dowel to quickly push one end of the potato plug up towards the other.

6)      The potato on the opposite end should propel through the air with a loud pop!

How does this happen?  The easiest way to explain the science behind this explosive conclusion is by looking at four concepts that will change the way you look at the natural world:

  • Atoms: Everything is made of atoms.
  • Density: The amount of atoms within a specific area of an object.
  • Diffusion: Areas with lots of atoms tend to move to areas with fewer atoms.
  • Law of Conservation: Atoms cannot be created or destroyed, only rearranged.

These four simple concepts can be easily applied to nearly every scientific explanation that you encounter, including your homemade potato launcher.  Let’s take a look inside your PVC tube to see what is really going on.

Air is trapped between the potato plugs within your PVC launcher.  This cylinder of air is made up of billions of atoms of nitrogen, oxygen, hydrogen, and many other elements.  As you push one end of the potato plug towards the other, the volume of this cylinder becomes smaller.

As the atoms are forced closer to each other the density of this cylinder increases.  The atoms within your PVC are already bouncing around and against each other very rapidly.  When you decrease the amount of space they can travel within a volume of air, they begin to bounce off the walls of the cylinder even faster.  This is what is known as the pressure of a gas. And, volume has an interesting relationship with pressure…

As the volume of a gas decreases, its pressure will increase!

This means the pressure inside your PVC launcher is increasing as you drive one potato plug towards the other plug.  As you drive the plugs closer and closer together, the pressure continues to rise until… BOOM!  The end plug is forced out of the launcher and into the air.  The loud POP you hear is the sound of air diffusing back into the tube, filling up the volume of air that was forced out of tube along with the potato plug.

No atoms are harmed during this process.  But they are moved around in such a way to generate enough force for your potato plug to fly across the yard.  This follows the Law of Conservation of Matter which states that atoms cannot be created or destroyed, only rearranged into different forms.

Now go outside and start slinging some potatoes pieces around the backyard.  Who said science can’t be fun?

 

BIO

During the day, Scott McQuerry (aka – Mr.Q) is your average, everyday high school science teacher humbly going about teaching the masses for the past decade or so.  He loves hearing from families who use his Classic Science Curriculum and looks forward to providing many more resources in the years to come.  Check him out at The Lab of Mr.Q – www.eequalsmcq.com.

 

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