## 22 August 2011

### The Blob

Last week, my six-year-old daughter hopped on a bike and took off. Well that was easy.

I’m pretty sure when I learned to ride a bike my dad had to exercise more patience than that. I don’t really remember, but let me just say with absolute confidence: there was blood. Probably some pants had to be thrown out. I don’t think my daughter even skinned a knee. It was ridiculous.

The same week, we all went to a YMCA summer camp site to play. They have something there called the Blob. It’s a huge inflated bag floating in the lake. One person sits on the far end of it. Another person jumps off a fifteen-foot tower onto the near end. When person 2 hits the Blob, person 1 is launched off the end and into the water. Cool idea.

We waited half an hour for it—there was a line, and about one in four kids goes up the tower and stands there, petrified, unable to make themselves jump and unable to give up their spot, for about five minutes. This gives people a lot of time to negotiate who will launch whom. Everybody wants to be launched by the biggest, heaviest guy in the pond. My daughter was the littlest; nobody wanted her to be right after them, so they all voluntarily let her go first. She got sorted to the front of the line way ahead of me.

We waited and waited. The last kid ahead of her finally chickened out.

Up the tower she went.

Will she jump? the guy behind me asked. I didn’t know. She seemed nervous, but it was just nerves, I thought. She wasn’t really afraid. She’s not afraid of this sort of thing. At least I didn’t think she was.

We didn’t have to wait long. She jumped right away. The next kid was maybe an eight-year-old boy. He jumped right away, too.

In hindsight, I should have done the math. My kid weighs about forty-five pounds. The boy said he weighed ninety. E = mgh, right? You can guess the Blob’s efficiency by watching the other jumps. Maybe 20%, 30%. So h2 = m1/m2 × h1 × 30%? And h1 is… fifteen feet…

Everyone gasped as she went flying. None of the other launches had been anything like this. Ten feet up she went, turned a slow back somersault in mid-air, and came down with a crash in the water, on the far side of the Blob where we couldn’t see. It was amazing.

I left the line and swam over to pick her up. She had landed on her face, so she cried a little. By the time we got to the beach, she was fine. You can imagine my feelings. I love that little girl.