If you've ever teetered on the edge of a diving board, you know that the board flexes under your weight.  The heavier you are, the more it bends.  The top of the board gets slightly stretched further than the normal length (tension) while the underside gets slightly shorter (compressed). We're going to duplicate this without needing to visit the pool.

We're going to expand on the topic covered in the Tension and Compression section of this article. All you need for this experiment is:
  • a pencil or a craft stick that you don’t mind breaking
  • a pair of hands
[am4show have='p8;p9;p13;p40;' guest_error='Guest error message' user_error='User error message' ] 1. Grab the pencil or the craft stick with one hand on one end of the object and the other hand on the opposite end.

2. Bend the pencil or craft stick a bit, but not too far....yet. Notice how you can bend it quite a bit without it breaking.

3. Now, feel free to bend it slowly until it breaks.



Download Student Worksheet

You have just played with tension, compression and elasticity. When you bent the pencil it had no problem going back to its original shape right? Wood is fairly elastic, meaning it can bend quite a bit before breaking. This comes in quite handy if you happen to be a tree, since you can bend in the wind which allows you to survive most storms without breaking.

Now, let’s look at tension and compression. If you look at the pencil or craft stick that you just broke you may notice that one side of the break may look different then the other side. Tension is when things get pulled apart. Compression is when things get squashed together.

If you bent your pencil towards the ground for example, the molecules along the top of the pencil were pulled apart, and the molecules along the bottom were squashed together. If you didn’t bend too far they just went back to normal when you stopped applying force. However if you bent too far, “SNAP”, the pencil broke in two! Just like objects have an elastic limit that if you go beyond it you will break it, things also have a tension and compression limit. Pull something or push something too far, and you’ll break it. [/am4show]

Have a question ?

Tell us what you're thinking...

Comments

12 Responses to “The Breaking Point”

  1. really? because I couldn’t see it with my ruler

  2. I can! It will vary a bit depending on the material of the ruler 🙂

  3. why can’t you see the stretch of the ruler with your own eyes

    PS. what if you eat carrot sticks HAHAHAHAHAHAHA!!!!!!!!!!!!!!!!!!!!!! Hey they’re good for the eyes 😀

  4. No one knows what happens there, since the laws of physics break at the singularity. Your guess is as good as mine!

  5. Shirley Caron says:

    Do you think it is possible that the center of a black hole is at absolute o degrees Kelvin, where all energy (movement has stopped in the atoms) and so the atoms are seeking energy so much that they begin to suck everything to themselves creating the black hole?

  6. Shirley Caron says:

    wow i never thought of it like that!

  7. why did it snap??

  8. I am not able to duplicate the problem – the videos are playing well over here… what happens if you try a different computer?

  9. Charis Chan says:

    Hi Aurora,

    I did try what you suggested but the video just won’t load beyond 44s no matter how long I waited. Strange thing is that this only happens to some of the videos. What do I do now?

    Charis

  10. Sounds like an internet issue. Try this:

    1. Click PLAY on the video.
    2. Now hit PAUSE and wait for it to load completely.
    3. Click PLAY. Now the video should play all the way through with no jumps, skips, or stops.

    You can do this for several videos at a time, since the experiments are all on one page.

    Note: We’re in the middle of updating all the players on the site (there’s over 900 now) so they will play faster and smoother for you.

  11. Charis Chan says:

    Hi, the video seems to cut off after 44s. I’ve tried to view it many times with the same result. Please help.

  12. amanda young says:

    Cool!