Q: Your timid date has never ridden a roller-coaster. "C'mon, you're gonna love it!" you lie. Which seat offers best hope of turning her into a trembling helpless puddle?–Rough rider
A: Take her on a hot day (wheel lubricants become slicker) and ride a packed train (reduces the slowing effect of wind resistance). The front seat obviously gives the most exciting view, as if plunging over a cliff, says Jearl Walker in The Flying Circus of Physics. But it's a slow car over the top and doesn't pick up much speed until it nears the bottom of a long hill, and by then it's already starting to turn upward. Not that scary.
The caboose, by contrast, is jerked careening over a crest so you'll feel a force as if being catapulted up and out of your seat– "negative G's." At this moment, riders will often let go of the safety bar and hold arms high in bravado, trusting that the G's aren't in fact negative or that the coaster's restraining devices will hold.
Problem for you here is if your date turns out puddle-proof and hikes up her arms, you're gonna have to too.
Q: Some people say they never forget a face. Are there people who are so bad with faces they can't even recognize their own mother? –T. Geisel
A: Sadly, yes, those suffering from prosopagnosia, or "face blindness." Bill, a 53-year-old, said that as a kid he always thought it stupid that robbers wore masks. "Why bother when the rest of their bodies still showed? It took me a long time to realize faces were special to most people."
One time he walked right past his mother on the sidewalk and didn't recognize her. "She was not amused."
There is a brain system specifically dedicated to identifying faces, says Rita Carter in "Mapping the Mind." "Face blindness can be caused by a dysfunction anywhere along the cortical recognition pathway," ranging from a mild condition (not good with faces), to Bill (socially impaired) to pathological (a dog looks like a bearded human).
Bill knows a face when he sees one but individuality is lost: he has trouble keeping track of people in his office because the faces all look alike, and when someone leaves the room and comes back in, he often isn't sure if it's the same person. Hairdos, beards and clothes help– a little.
Bizarrely, some face-blind people, adds Carter, do well at recognizing faces that are turned upside down. And one farmer after a brain injury couldn't distinguish human faces any more but had enhanced recognition of his animals– he was now able to name all 36 of his sheep and tell them apart!
Q: Will nuclear weapons explode in space? –Budding scientist
A: Sure, it's been done– back in the old Cold War days before nukes in space were banned by international treaty. Nuclear reactions don't require oxygen or gravity, so they'll go off there just fine.
But the nature of a nuclear blast in space is very different– no shock wave because no atmosphere, and no mushroom cloud– just a huge spherical blast of high-energy light, says astrophysicist Fernando Camilo.
And no fireball. Enormous vaporizing heat, but no fire because of lack of oxygen, adds physicist Ski Antonucci.
Best-known space explosion was Starfish-Prime, notes the Los Alamos National Laboratory. The 1.4-megaton test was detonated above Johnston Island in the Pacific July 9, 1962, 250 miles up. It knocked out lights, blew fuses, and triggered burglar alarms in Hawaii hundreds of miles away.
(Send strange questions to brothers Bill and Rich at firstname.lastname@example.org)