Pls help on both sides i really do appreciate it

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.

The energy equivalent of the rest mass of an electron is

What you see with your eyes is a form of energy. a. light b. heat c. chemical d. electrical