IF YOU GET GOOD GRADES ON TEST PLEASE HELP sarah hears the siren of an ambulance that is moving toward her. if the actual frequency of the siren is 2000 hertz; which frequency was heard by sarah?
A. 1900
B. 2000
C 1000
D. 2100
( please be 100% sure with your answer )

Not all tiles will be usedidentify the element present in each star based on the gaps observed in wavelengths of its light refer to this table containing absorption wavelengths (in nm) of several different elements the table ishelium 447, 502 ,587 ,668carbon 427 ,515, 600 ,678sulfur 425, 565, 639, 675xenon 484, 590, 687calcium 429 ,527, 593, 645silver 421 ,521, 662

Anybody wanna ? (picture included? )

A0.580-kg rock is tied to the end of a string and is swung in a circle with a radius of 0.500 meters. the velocity of the rock is 4.50 m/s. what is the centripetal force acting on the rock? 15.5 n 5.22 n 69.8 n 23.5 n