A hydrogen atom, initially at rest, absorbs an ultraviolet photon with a wavelength of A = 154.3 nm. %3D Part A What is the atom's final speed if it now emits an identical photon in a direction that is perpendicular to the direction of motion of the original photon? Express your answer to three significant figures and include appropriate units. HA Value Units Submit Previous Answers Request Answer X Incorrect; Try Again; 9 attempts remaining Part B What is the atom's final speed if it now emits an identical photon in a direction that is opposite to the direction of motion of the original photon? Express your answer to three significant figures and include appropriate units.