Which of the following characteristics indicates that an atom is unstable?

Look at the spectrums of a star moving towards earth and a motionless star. which of these is a correct inference that can be draw from the observation of the two spectrums? (2 points) the spectrum of a motionless star is difficult to be viewed separately using oridinary telescopes. the spectrum of a motionless star is identical to the spectrum of a star which moves towards earth. the spectrum of a star shifts towards the red region when the star moves towards earth. the spectrum of a star shifts towards the blue region when the star moves towards earth.

Which of these features are formed when hot groundwater is forced out through cracks in the earth's surface?

A40 kilogram skier starts at the top of a 12 meter high slope. at the bottom, she is travelling 10 meters per second. how much energy does she lose to friction