which situations might cause two observers (a and b) to measure different frequencies for the same vibrating object? select the two correct answers.

Earth's atmosphere is unique among the planets and is able to support life because it contains a large amount of a) oxygen b) helium c) methane d) carbon dioxide

Why has there been such a large increase in theft and other crimes in the u. s

Auser wants to add a thick, dark green border around a chart in powerpoint. the user can do this in chart tools by choosing what