Geek Dad: Awesomely Geeky Projects and Activities for Dads and Kids to Share (23 page)

To be on the safe side, test the setup to make sure everything worked together. Then you are ready to invite the neighborhood over. My GeekDad suggestion is to kick off the summer by sipping lemonade, eating popcorn, and watching Indiana Jones try to discover the Ark of the Covenant. Happy viewing!

B
eing a GeekDad means understanding science and, when possible, incorporating that understanding into everyday teachable moments. Whether it’s chemistry in the kitchen, dynamics on the pool table, or biology in the garden, improving our kids’ knowledge of the world around them is vital.

And an important part of making those teachable moments palatable for them is making science fun. Even when it makes a task a little more complicated, sometimes it’s better to add some cool science—to include a “wow” factor in a mundane project—so that it becomes something more.

This project was inspired by that principle and by the geekfavorite show
Mythbusters
.

Friction is one of the fundamental components of dynamics, and yet it can be very difficult to explain beyond sandpaper and rub burns. This project offers a surprisingly cool demonstration of the true power of friction by using it to support the weight of a person on a swing (either your kid or yourself . . . or both!).

 

WARNING:
This is not a practical project. It would be easier to build a rope swing with just rope. But it wouldn’t be as cool. Also, keep this out of the rain. The phone books won’t last long if they get wet or suffer otherwise extended exposure to the elements. This swing should be built to be easily taken down and stowed away between uses.

What we’re doing is taking the classic idea of a rope swing and adding the friction twist by putting two interlaced phone books into the hanging assemblage. If you haven’t seen the episode of
Mythbusters
, the simple science here is that, if you take two phone books (and who really needs their phone books these days?) and interlace the pages as you would shuffle a deck of cards, they can’t be pulled apart by any practical means.

How does it work? The simple answer is friction. The friction between individual pieces of paper is negligible. However, when you interlace the pages of two phone books with hundreds of pages in each, the cumulative effect is stronger than glue, and you won’t be able to pull them apart with anything less than a couple of tanks (hence the “practical” caveat above).

This is the long, slightly boring part of the project. You want to start with two phone books of approximately the same size (identical if you can get them). Set them in front of you on a table, with the binding sides facing out. Imagine shuffling them like a deck of cards: You’d simply pick up the inward-facing, loose sides of the books, bring them together, and shuffle.

Unfortunately, for this project, it takes a little more work than that.

Take the books and fold everything outward, until all you have are the back covers facing inward. Bring the two books toward each other until one cover lays over the other by at least half its width. Then start leafing pages over, first one book, then the other, alternating as you go. Do this until you have interlaced all the pages.

Next we’re going to incorporate the phone books into the swing. We will build reinforced brackets so we can tie the rope for our rope swing to the spines of the phone books.

 

STEP 1:
Cut 4 strips of plywood (½ inch or thicker) 3 inches wide and as tall as each book to sandwich the un-interlaced ends of each of the phone books.

 

STEP 2:
Take one side of the interlaced phone books and sandwich the spine with two strips of the plywood. Hold the pieces of wood in place with a clamp.

 

STEP 3:
Now drill three holes through the plywood/phone book sandwich, spaced evenly across. The holes will be two different sizes. The center hole should be about the diameter of the rope you’re going to use (probably ⅝ inch to 1 inch). The other two should be sized to fit the bolts you’re going to use to hold the brackets together, perhaps ⅜ inch or so. Go ahead and drill, and bolt the brackets together, leaving the center holes open on each end of your assembly.

STEP 4:
Figure out where you’ll hang the swing: off a play set, a sturdy tree branch, or some other overhanging anchor point. Decide how long your rope is going to need to be, roughly. Assume you’ll need a knot at the bottom for the seat to rest on, enough length such that the seat will be suspended two to three feet off the ground at the lowest point of the swinging arc, and enough at the top to tie it off at the anchor point. This should be a conservative estimate; you can always trim it later if it’s too long.

Your choice of rope is important. You’ll need something fairly thick and strong. A heavy climbing rope can be a good choice, as you’ll want to be able to knot it relatively easily.

 

STEP 5:
Your first piece of rope will go from the “top” side of the phone book assembly to the anchor point where it hangs. Figure out what you think that distance will be, then triple it to give yourself some length to work with. Feed the rope through the large center hole in one bracket, pull it even so the ends meet when held straight up from the books, and tie a good knot (I’ll leave it to your Boy Scout skills or Internet research to determine the right one).

In my version of this build, I hooked the knotted end to a heavy-duty carabineer, and then found a heavy-duty hook I could drill into my anchor point. You may have to adjust depending on your anchor point, available tools, and hardware, but I have faith you can figure it out.

 

STEP 6:
Hang from the anchor what you’ve got done so far, and try testing it with your weight. Isn’t friction amazing?!? Next measure the distance from the bottom of your assembly to where you want the seat to be at the bottom of the swing’s arc. You have two choices now: Use either a single length of rope tied off to a carabiner or a metallic ring hooked through the bottom hole of the phone book assembly.

 

STEP 7:
Measure the rope so you have a good foot below the seat point. Build your seat. The simplest is to cut out a square of thick plywood, or sandwich a couple layers of thinner plywood, and drill a hole through the center to pass the rope through. Knot the rope both above and below the seat to keep it in place, making sure the knots are tight and that they’re big enough not to pass through the hole.

And with that, you’re done! Let your kids try it, even try it yourself, and tell everyone who comes over how the only thing keeping it together is the magic of friction!

(Be sure to bring it in the house when you’re done—getting it wet would be bad.)

G
eek culture tends to be, shall we say, a casual culture. We tend to be more comfortable in khaki shorts and superhero T-shirts than suits—and that’s just at work. But there are a few times in a geek’s life when fancy dress (and we’re not talking cosplay here) may be required. But even if you or your kids have to dress up, that doesn’t mean you have to lose your geek cred.