Calculate the speed of the electron of a hydrogen atom if it is in the fifth circular orbit. m/s 4.4 x 10 1.1 x 107

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.

Can you receive a shock severe enough to prevent you from releasing the wire from an ordinary outlet with dry hands? a. no b. yes explain

The direction of the current in an alternating current circuit remains constant. is direct. changes repeatedly. changes randomly.