What will be the final kinetic energy if the velocity of a body is halved keeping mass constant

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

Gabby calls her cousin who lives in a different state and tells her to turn her radio to channel 98.7 so they can listen to their favorite song that is playing. her cousin turns her radio to 98.7, but does not hear the same song gabby hears. which most likely explains why?

What quantity do units represent in value