a stone is dropped from the top of a tower 400 m high and at the same time another stone is projected upward vertically from the ground with a velocity of 100 m/s. find where and when the two stones will meet.

Which of the following conditions lead you to see an absorption line spectrum from a cloud of gas in interstellar space? the cloud is extremely hot. the cloud is visible primarily because it reflects light from nearby stars. the cloud is cool and lies between you and a hot star. the cloud is cool and very dense, so that you cannot see any objects that lie behind it.