For a given medium such as air, sound has a slower speed at lower temperatures. Ivan yells across a canyon in the morning when it is cold and again later in the afternoon when it is hot. During which time did his voice travel the fastest morning or afternoon?
afternoon

For a given medium, sound has a slower speed at lower temperatures. Greta yells across the canyon in the cool morning and again in the hot afternoon. The sound likely traveled slower or not as slow in the morning?
not as slow

As the Universe expands, galaxies move further and further apart. If Mona is studying the galaxy and she notices that the universe is expanding less then it used to, what does that mean is happening to the galaxies in the universe moving closer together or moving further apart?
moving closer together