You hear 2 beats per second when two sound sources, both at rest, play simultaneously. The beats disappear if source 2 moves toward you while source 1 remains at rest. The frequency of source 1 is 500 hz. The frequency of source 2 is.

Approximately workers each year are treated for injuries caused by lifts, jacks, or jack stands. a) 2,000 b) 5,000 c) 10,000 d) 15,000

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.

Rick is on a bicycle trip. every 4 days he bikes 230 km. if rick keeps this same pace for 16 days, how many kilometers will he bike?