Ineed some w/ this:

a police car siren emits a frequency of 2010 hz when stationary. when it is driving toward a stationary car, the other driver hears a frequency of 2120 hz. how fast is the police car driving?

using the doppler's effect equation, i got the answer ±16.3, but that apparently isn't the correct answer.

edited: ohhh ok, i got it, answer is 17.7 whoops

What occurs during a combustion reaction

The electric field between square plates of a parallel-plate capacitor has magnitude e. the potential across the plates is maintained with constant voltage by a battery as they are pulled apart to twice their original separation, which is small compared to the dimensions of the plates. the magnitude of the electric field between the plates is now equal to a)e b)e/4 c)e/2 d)4e e)2e

Apersons beliefs and general outlook, which act like filters on the information they receive are called ?