# Wheeeeelie: Drive a car up a wall

Q. How steep a hill could a car climb? Ten degrees? Twenty? Don't try this in the neighborhood, but could a car go straight up a vertical wall? Yes, 90 degrees?! ­J. Gordon

A. Ten degrees doesn't sound like much but is actually a pretty steep incline. Still, a car could do this fairly easily. The power train of a typical passenger car can develop torque equivalent to about half the vehicle's weight, says University of Michigan professor of automotive engineering Thomas D. Gillespie. So most cars could ascend a slope of up to 30 degrees, or grade of 58 percent.

Four-wheel-drive vehicles with low range can do better, with many having power to go right up a vertical wall. Top dragsters are the best, says Gillespie. At launch, they accelerate at 5 G's, which would be equivalent to climbing the wall while dragging four other dragsters behind it!

But these are just raw horsepower considerations. Next problem: sufficient friction of tires against the roadway- wall. That's trickier, but mechanical and computer engineering specialist Ian Charnas poses a way. Build a road that starts flat and curves slowly upward. As dragster speed builds, the road curves up steeper and steeper. The vehicle should be equipped with spoilers– like upside-down airfoils– shaped not for lift but for down pressure, to lend added frictional force against the roadway-runway.

Given sufficient power train and speed, the right road curve and spoiler aerodynamics, the dragster just might be driveable vertically heavenward! Heavens to old rocketin' Betsy!

P.S. To take this really over the top, says Charnas, a 2001 Bentley EXP Speed 8 at 150 mph develops a reported 3094 pounds downforce. Since the car weighs only 2020 pounds, "there would be no problem driving it upside down!"

Q. What's a good guess as to how fast computers will be by 2010? How might such a thing be estimated? ­L. Jameson

A. In 1965, Intel founder Gordon E. Moore predicted technological advances would allow computer chips to double in power roughly every two years, and this has held fairly true– called "Moore's Law," say Jeffrey Bennett and William Briggs in Using and Understanding Mathematics: A Quantitative Reasoning Approach.

Doubling means exponential growth, as computer speeds went from about 1 to 100 calculations/second between 1950 to 1960, then from about 100 million to 10 billion calculations/second between 1990 and 2000. Extrapolating from this, with rates leaping a hundredfold per decade, we can all look for computers to do a breakneck trillion calculations/second by 2010!

Q. What's the chemical composition of seawater? Is it true there's gold in "them thar oceans"? ­C. Ahab

A. There's just about every known element, in trace amounts at least, says University of Rhode Island oceanographer emeritus Michael E. Q. Pilson. Salts (mostly sodium chloride) are plentiful, enough if dried and piled to bury the state of Texas 20 miles deep; sulfate and magnesium, too, the latter lending seawater its bitterer-than-table-salt taste.

The tales of gold are true, but the concentrations are small and difficult to measure, says Pilson. The total is around 14,000 tons– about half the amount on deposit in the world's central banks. Some 50 years ago, Dow Chemical Company spent \$50,000 to experiment on the extraction of gold from seawater, and for this effort managed to extract an amount of gold worth 1/100th of one cent!

The real goldmine of the seas is common salt, obtained by a complicated evaporation process. "Worldwide 5000 tons are extracted every hour of the day throughout the year."

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