The two-column form used for entries that do not "fit" in any of the special journals.

Forces that are equal in strength but opposite in direction are a.) balanced b.) unbalanced c.) always result in motion d.) do not exist

Ascientific idea becomes valid when it is what?

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.