Can you poke a straw all the way through a raw potato without
bending or breaking the straw?
Try it and see! Hold the potato between your thumb and fingers.
Don't put your hand behind the potato, otherwise you might stab
yourself with the straw!
Did you manage it? Here's how to do it.
What you need:
- Straight straw (if you have a bendy straw, you can cut the
bendy bit off)
- Raw potato
- Hold the potato between your thumb and fingers. Make sure your
hand isn't behind the potato.
- Hold the straw about two thirds of the way up, so there's lots
of straw to go into the potato. It's easiest if you hold the straw
in the hand that you write with.
- Hold the straw firmly and quickly stab the straw into the
narrow end of the potato. You should be able to get the straw out
of the other end! You need to be quick and confident.
Having trouble? Try changing your grip. Sometimes it helps to
hold your thumb over the top end of the straw.
Show your friends and parents. Can they work out how to do it?
Don't re-use the same straw - it might not work the second time
The end of the straw has a very small surface area. This means
the force you apply to the straw is concentrated in a small area.
If you tried doing this with a similar sized object, such as a
pencil, the force would be distributed over a larger area, so it
would be much harder to push the pencil into the potato.
You need to push the straw in quickly. This produces a greater
force than if you slowly twist the straw into the potato.