A large ferry boat is moving north at 4.0 m/s [N] with respect to the shore, while a child is running on the deck at a speed of 3.0 m/s. Determine the velocity of the child relative to Earth when the child is running in the following directions with respect to the deck of the boat. (a) north
(b) south
(c) east

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.