I think Dickens had it pegged perfectly for those who wonder why another 25 or 50 cents a gallon makes such a difference even for people who don't drive all that much:
"Annual income twenty pounds, annual expenditure nineteen pounds, nineteen shillings and sixpence, result happiness. Annual income twenty pounds, annual expenditure twenty pounds and sixpence, result misery."
What the hullabaloo says is that enough families in the US are so tightly budgeted that this kind of money may make the different between treading water and sinking, between a reasonable lifestyle and just hanging on.
If you drive a thousand miles a month in a car that gets 20 miles to the gallon, 50 extra cents a gallon is 25 bucks. That's enough over the course of a year to float the interest on something close to five grand of credit-card debt. (Or maybe it's just your once-a-month trip to the movies down the drain, forever.)
If you commute an hour each way every day in that same car, take $10,000 of the price of the house you can afford. Or stop saving for your kid's college education.
Of course, gas would probably have to go up by another buck or two a gallon before it made economic sense to just leave your current car by the side of the road and buy a new fuel-efficnet model.
As I rock back and forth in the glider with Charlie in my arms, I can feel alternately my back pressing into the seat cushion and his body pushing outward against my arms. If I pay close attention, I can even feel my eyes and the skind on my face undergoing subtle pressure in response to the rocking movement.
Because holding a partially compliant Charlie crosswise against my chest doesn't really allow for a lot of other activities, and because I was a physics major once, I amused myself the other evening by calculating the forward and backward g forces (what they used to call "eyes in" and "eyes out" in the aeronautics trade) during a typical rocking session. Turns out they're fairly substantial.
OK, remember that I couldn't even scribble on the back of an envelope, so many of these numbers are chosen for ease of mental calculation while holding an infant rather than as a precise model of what's going on in a driven damped pseudoharmonic oscillator.
Figure that my body and head (and Charlie) are moving only about 8 inches (20 cm) back and forth, and that I'm rocking at about one cycle per second -- sometimes it takes some pretty vigorous rocking to get a boy to relax -- and you get and average speed of 40 cm/sec. Not very fast.
But at the beginning, middle and end of each rocking cycle the glider is at rest, so instead we're talking about a half-cycle in half a second during which the glider accelerates to some peak, then decelerates again to zero, with the average speed during that half-second still 40 cm/sec. The simplest way of doing this is a straight-line constant acceleration, followed by a symmetrical deceleration, so we now have a quarter-second during which the glider goes from zero to peak and a matching quarter-second from peak to zero.
Nice thing about constant accelerations is that the average speed is simply half of the peak speed, and since we already know the average is 40 cm/sec, it follows that the peak is 80 cm/sec, reached in a quarter of a second, for an acceleration of 3.2 meters/sec/sec, or about 0.33g.
Now of course the actual motion has to have some kind of smoothish curve for the acceleration rather than a sudden transition from positive to negative, if only because the leg muscles that actually rock the chair don't work that way. So we have an average acceleration of plus or minus a third of a g, reaching a peak at either end of the half-cycle and pretty close to zero in the middle. You could make the same argument as for speed, but that seems unlikely, so I'll split the difference and call it half a g. Alternatiing every half second.
Not bad for just sitting in a chair.