Straw Through Potato
Materials
•Plastic straw
•Raw potato
•Paper towel
Experiment
1.The challenge is quite simple: Stab the straw through the potato
without bending or breaking the straw. Most of your guests will
think it can't be done but you, of course, know better.
2.As you hold the potato, keep your fingers on the front and thumb
on the back and not on the top and bottom. Grab the straw with
your writing hand and (this is the secret) cap the top end with your
thumb. Hold on firmly to both the straw and the potato and with a
quick, sharp stab, drive the straw into and partway out of the
narrow end of the spud and not the fatter middle part. You're so
cool!
3.Your audience will be impressed and want to try it. Great! Tell
them to hold the spud the way you did so they don't stab a finger or
thumb with the straw. They may not know the secret so don't give it
away just yet. Oh, you may need more stiff straws for them, too.
How does it work?
The secret is inside the straw: it's air! Placing your thumb over the
end of the straw traps the air inside. When you trap the air inside
the straw, the air molecules compress and give the straw
strength; which in turn keeps the sides from bending as you jam
the straw through the potato. The trapped, compressed air makes
the straw strong enough to cut through the skin, pass through the
potato, and out the other side. Without your thumb covering the
hole, the air is simply pushed out of the straw and it crumples and
breaks as it hits the hard potato surface. Make sure to keep your
fingers out of the way. After you stab the straw, take a look at the
end that passed through the potato. There's a plug-o'-spud inside
the straw. If you should have a finger or thumb or hand in the way
of the straw as it collides with the potato, then there will be a plug-
o'-you in the straw, too.
Experiment From Steve Spangler Science
•Plastic straw
•Raw potato
•Paper towel
Experiment
1.The challenge is quite simple: Stab the straw through the potato
without bending or breaking the straw. Most of your guests will
think it can't be done but you, of course, know better.
2.As you hold the potato, keep your fingers on the front and thumb
on the back and not on the top and bottom. Grab the straw with
your writing hand and (this is the secret) cap the top end with your
thumb. Hold on firmly to both the straw and the potato and with a
quick, sharp stab, drive the straw into and partway out of the
narrow end of the spud and not the fatter middle part. You're so
cool!
3.Your audience will be impressed and want to try it. Great! Tell
them to hold the spud the way you did so they don't stab a finger or
thumb with the straw. They may not know the secret so don't give it
away just yet. Oh, you may need more stiff straws for them, too.
How does it work?
The secret is inside the straw: it's air! Placing your thumb over the
end of the straw traps the air inside. When you trap the air inside
the straw, the air molecules compress and give the straw
strength; which in turn keeps the sides from bending as you jam
the straw through the potato. The trapped, compressed air makes
the straw strong enough to cut through the skin, pass through the
potato, and out the other side. Without your thumb covering the
hole, the air is simply pushed out of the straw and it crumples and
breaks as it hits the hard potato surface. Make sure to keep your
fingers out of the way. After you stab the straw, take a look at the
end that passed through the potato. There's a plug-o'-spud inside
the straw. If you should have a finger or thumb or hand in the way
of the straw as it collides with the potato, then there will be a plug-
o'-you in the straw, too.
Experiment From Steve Spangler Science
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