Two vehicles are moving in the same direction. The velocity of the first vehicle is 8 m/s and the velocity of the second vehicle is 5 m/s. Find their relative velocity. What will be the relative velocity if they move in the opposite directions?​

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.