Spinning confuses humans

Answer: The human visual system just isn't equipped to track the curved course of a fast-spinning ball, whether a baseball or a soccer ball, says Queen's University, Belfast psychologist Cathy Craig in New Scientist magazine.

She recalls watching Roberto Carlos score a mesmerizing goal for Brazil in 1997, when everybody felt the ball was going wide of the mark until it curved in at the last instant. But don't overhastily blame the goalkeeper, she says. She tested experienced soccer players to see if they could follow (predict) the trajectories of balls with rapid sidespin of 600 rpm — via a virtual reality display — and they couldn't.

Sidespin creates a "Magnus force," just what a baseball pitcher relies on for a curve ball. This force accelerates balls in a direction we humans are unable to process because spinning things don't occur naturally, meaning we have had little evolutionary experience with Magnus. Catching fly balls is different: We've had to anticipate the effect of gravity on moving objects throughout our long history.

Question: This food's fat content is 50 percent saturated, 50 percent un-. The saturateds include palmitic acid (26 percent), stearic acid (8 percent), myristic acid (8 percent), lauric acid (5 percent) and arachidic acid (1 percent), plus traces of others. The mono-unsaturated fats are oleic acid (35 percent) and palmitoleic acid (3 percent), the polyunsaturated is mainly the omega-6 linoleic acid (10 percent). The omega-3 acids are linolenic (0.9 percent) and arachidonic (0.6 percent). Overall protein content varies, as do carbohydrates and fats: At the start of a "serving," the fat runs lower, the sugar (lactose) and water higher, until the fatstuffs really kick in. The food itself has about 750 calories per liter (1-plus quarts), which would do (a very small you) just fine for a day. You've likely had your share, though long ago, and in this sense you know it well. . . .

Answer: Mother's milk it is, of the "fore" and "hind" varieties per feeding, the reason the content shifts, says John Emsley in "Vanity, Vitality, and Virility: The Science Behind the Products You Love to Buy."

Question: From a Cleveland, Ohio reader: "I read recently that a large pet health insurer covers hearing aids for dogs. But wouldn't they just get annoyed and try to dislodge the devices?"