This week's travel theme at Where's My Backpack? is: motion!  As luck or fate or my enviable location in central PA would have it, family is in from out of town.  And it's family with small kiddos.  Which, of course, means that Knoebel's is on the agenda for any summer, G-rated daytime adventure.  Knoebel's, for the uninitiated, is only (really!) Travel Channel's #2 amusement park in the country...the country, people, and as far as countries go this is a big'un.  Admission is free.  Parking is free.  You buy books of tickets or do an all-day wristband.  And it looks a little like a throwback to some gauzy, nostalgic era that never really existed except in magical places people invent to bestow a sense of gauzy nostalgia.It's fantastic.But enough of me spinning my wheels here, yapping away.  You want motion?  You got it.The Power Surge is one of my favorite rides.  It flings you about like crazy, but it's a great shortcut to getting zen and contemplating the impermanence of our mortal existence.  Plus, you spin around a lot and it's reallyreally cool.Meanwhile, my niece rocks it out in a bouncy moon walk.The Twister is a giant wooden roller coaster with lots of dips and twists and turns.  Here's a car going down one of the first--but by no means the highest--drops.Saaaay...is that a pirate ship emerging through the tops of the trees?When I stop and think about all ways our bodies are being enacted on by various forces at work in an amusement park--some of us are being swung sideways at great heights, while others spend their time in the air being tumbled around inside what looks like a giant time-release capsule--I can't help but be grateful.  I'm so glad science works.  Engineers rule!And finally: third car back, bald dude mugging for the camera, throwing his hands up in the air to party hearty like he jus' don't care?  Yeah, that's my brother.  The little flame of red hair next to him is my niece.Go to Knoebel's.  I'll meet you there.[youtube=http://www.youtube.com/watch?v=tUqvPJ3cbUQ]K