How does the relative motion of a motorcycle affect the frequency of the sound heard by an observer on the sidewalk?

as the motorcycle approaches the observer, the frequency drops.

as the motorcycle approaches the observer, the frequency increases.

as the motorcycle passes the observer, the frequency remains the same.

Which bonds are found inside a water molecule

What is a view of science and psychology that says the value of knowledge depends on its usefulness? a. pragmatism b. psychotherapy c. physiology

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?