Sitting duck  Problem 191 — It sometimes pays to be at right
angles with your relations, as this month’s problem by Jannine
Sobottka of Mesilla Park, N.M., demonstrates.  “Why, what
wonderful weather for a day in the park,” chirped Phineas
Gotrocks to his 13-year-old nephew. “Here, Spaulding, make a
video of me riding the Ferris wheel!”  Gotrocks climbed into his
seat, and the ride started. He chortled as he noticed his good
friend Lottie Dough with a gentleman not her husband on another
seat.  Meanwhile Spaulding had quietly put down the camera and
picked up a large slingshot and water balloon. He prepared to
fire the balloon. The Ferris wheel has a 20-ft radius and turns
at 1 rpm. Lottie and her companion had rounded the top and were
descending, as Spaulding fired his balloon. Gotrocks was nearing
the bottom of the ride.  Spaulding stood with his slingshot 75
ft from the point directly beneath the center of the wheel on
the side where the riders descended. The balloon’s initial
velocity was 60 fps, and it h