This week, the elder Free-Ride offspring's science class was reviewing for a test. (In second grade? Did we used to review for science tests back in second grade? Maybe things have changed since then.) One of the issues in the material they were reviewing was sound, which prompted a discussion that ran beyond the bounds of what will be on the test.
Dr. Free-Ride: So, what do you know about sound?
Elder offspring: Well, sound can travel pretty well through air, and also through a fluid like water.
Younger offspring: That's why, in swim lessons, you can hear the teacher say, "One, two, three, turn and breathe!" even if you're keeping your chin down like you're supposed to.
Dr. Free-Ride: Am I remembering right that sound waves need some medium to travel through?
Dr. Free-Ride's better half: Do you think sound can travel through a solid?
Elder offspring: Hmmm, maybe.
Dr. Free-Ride's better half picks up a large metal salad bowl and bangs it like a gong.
Dr. Free-Ride: Sure, you can set solid objects a-vibrating. Of course, at room temperature, their molecules are all vibrating anyway, even if you can't hear them.
Younger offspring: Guitar strings vibrate, too.
Dr. Free-Ride: Yes they do. And you can hear sound waves travel through solid objects like walls.
Younger offspring: That's why in School of Rock Mr. S. asked the kids to sound-proof the room!
Dr. Free-Ride: You're right! Hey, you know there's this trick you can do of holding a water glass to your ear, then putting the open end of it against a wall to listen to what's happening on the other side of the wall. I wonder why that works as well as it does.
Dr. Free-Ride's better half: A stethoscope would work even better.
Dr. Free-Ride: Yes, but most motel rooms don't come equipped with stethoscopes, whereas they do usually have water glasses.
Elder offspring: I think I'll use a water glass to listen through my bedroom wall to hear what you guys talk about!
Dr. Free-Ride's better half: Unfortunately, on the other side of your bedroom wall is our closet. So, you'd mostly hear anyone who was hiding in our closet trying to spy on us.
Dr. Free-Ride: Hey, you could make a friend!
Do you guys really talk like that? 'Cause that is just too cute!
Breena -
Yes they do. But their walls are too thick for tumbers: even with a stethoscope one can barely pick up some of their comments.
MiC