What Made It Break?
Pop! goes the bubble.
Rip! goes the paper.
Snap! goes the stick.
Pop, rip, snap, crack. . . .
These are the sounds of things breaking. What makes them
break? The answer is too much strain.
Strain is s-t-r-e-t-c-h. You can stretch a rubber band a long way without breaking it. See how it gets thinner and thinner as it is stretched more and more? That means the rubber band has strain.
Can you find the thinnest part of the rubber band? That
is a weak spot. If you stretch the rubber band a little bit
farther .
. . Ouch! When the strain is too much, the rubber band breaks at that
spot.
Strain is not a bad thing. Without strain, we could not enjoy a comfortable hammock. In the cartoon, see how the hammock bends beneath the boy? If you look carefully, you can see that the hammock is a bit longer when the boy is in it than when he is out of it. That means the hammock has strain.
Most materials can take some strain, but how much is too much? What if an elephant hopped into the hammock? The hammock might hold a person, but probably not an elephant.
A break starts at the spot that has the most strain. Bend a yardstick a little bit. You’ll make an arc. Can you tell that the part of the yardstick facing outside of the arc is stretched more than the part of the yardstick inside the arc? The outside is being stretched the most. It is the part that has the most strain. If you kept bending the yardstick, a weak spot on this side is where the break would start.
Now you know how things break. The next time something breaks, don’t say, “I didn’t do it.” Say, “There was just too much strain!”
