If electrons of energy 12.8 ev are incident on a gas of hydrogen atoms in their ground state, what are the energies of the photons that are emitted by the excited gas?

Suppose a wheel with a tire mounted on it is rotating at the constant rate of 2.15 times a second. a tack is stuck in the tire at a distance of 0.373 m from the rotation axis. noting that for every rotation the tack travels one circumference (a) find the tack's tangential speed. (b) what is the tacks radial acceleration?

Anoche fuimos al restaurante el gusto. jaime le (1) (pedir) al camarero una mesa en la sección de no fumar. yo (2) (pedir) chuleta de cerdo con champiñones, papas y ensalada y jaime (3) (pedir) mariscos, arroz y ensalada. el restaurante estaba lleno (full) por eso no nos (4) (servir) muy rápido (very fast), pero la comida estaba deliciosa. no me lo vas a creer (you won't believe it) pero ¡jaime (5) (repetir) arroz y mariscos! ¡dos porciones (orders)! ¿ya entiendes por qué él no (6) (dormir) bien anoche?

Awaiver with a period of 0.008 second has a frequency of a. 800hz. b. 80hz. c. 125hz. d. 12.5hz.