You have 9 stones that are identical in appearance. one of these stones weighs just a bit more than the other 8. these other 8 stones are exactly the same in weight. using a balance scale only twice, how can you determine exactly which stone is the heavier?

At 20∘c, the hole in an aluminum ring is 2.800 cm in diameter. you need to slip this ring over a steel shaft that has a room-temperature diameter of 2.804 cm . 1. to what common temperature should the ring and the shaft be heated so that the ring will just fit onto the shaft? coefficients of linear thermal expansion of steel and aluminum are 12×10−6 k−1 and23×10−6 k−1 respectively.