Some Notes on the Physics of Dropping a Water Bottle While Biking


Copyright 2002 by Jon Bondy, All Rights Reserved.

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Jon Bondy,


I own a BikeE recumbent bicycle.  Red, of course.  I think I look pretty cool when I go tooling around the dirt roads near my house on the bike.  Silver hair.  Tanned arms and legs (don’t mention the pasty white belly, hidden tactfully under the shirt).  Biking accouterments.

I wear biking gloves, the kind with leather palms, but where your fingers poke out of the gloves, and there are openings on the back of your hands (for ventilation?!?).  You get special oval tan lines on the backs of your hands, so that everyone will know that you are a biker.  If they know to look

And I wear special sunglasses, with leather side-covers, the kind explorers wear on expeditions to the polar ice caps.  I do this less to prevent frozen eyeball than I do to prevent road grit from getting under my contacts (not that it does much good), but I still fancy myself as looking pretty darned cool as I trundle down the road.

And don’t forget the blue baseball-style cap, cap forwards.  Carefully faded.

I’m sure the locals think I’m a strange looking duck, but since I live in my own world, their perceived ridicule matters little to me.  Once a flatlander, always a flatlander.  Once a geek, always a geek.  Once a hippy, always a hippy.

As I head off on my ride, I imagine the forest to be full of young women who, knowing how cool I look, have spent the night in the trees, just so they can get a glimpse of my magnificence as I speed by.  Well, as I go by, anyway.

So, there I am, biking along, satisfied that my mere presence is making the world a more perfect place.  I reach for my water bottle (you were wondering when I was going to get to that, weren’t you?), and sip some iced tea.  All is well in the world.  Until I drop the water bottle.

Now, I’m going down this dirt road at a fair clip, and I’m well aware that the girls in the trees are far from impressed with this act of supreme awkwardness.  I will now have to stop the bike and either frog-walk it backwards to the bottle; or put the bike on its stand and then walk back to the bottle; or turn around, bike back, and pick up the bottle.  In any event, the whole effect has been ruined.  I am no more the dashing eccentric cyclist.  I am the clumsy fool who faux pased in the middle of the road.

I figure that slowing down is a first order of business, so I hit the brakes.  Now I practice emergency stops fairly often, say once every never.  I am well aware of the physics of braking, and how easy it is for the front wheel to brake harder than the rear, causing the rear wheel to want to “come around”.  Nevertheless, keeping all of this in mind, I still manage to get the rear wheel to come around.  Just a bit.  Just enough to make life interesting.  I focus on not falling over, figuring that would impress the ladies even less.

Preoccupied as I am at staying upright, I am not immediately aware of the water bottle which comes scooting up at me from behind, skittering all over the dirt, scattering pebbles as it decelerates.  As I stop, so does the water bottle.  Right beneath my feet.  I am puzzled, amazed, speechless.

I suddenly realize that, since both the water bottle and I were going at the same speed when it dropped, I should not be surprised that we both stop at the same spot.  Well, I did wonder for a moment when the water bottle had managed to find the time to practice its emergency braking.  And I also wondered how it had managed to stop without having its rear end “come around” (it arrived top first).

So, I nonchalantly bent down, snagged the water bottle, and was on my way.  The girls in the trees breathed a sigh of relief, and I pretended that I had planned the whole thing that way from the start.

Physics.  Gotta love it.