Which of the following is an example of the Doppler effect?
Vibrations from a tuning fork pass through the air and cause a nearby dish of
water to produce ripples of the same frequency.
Two identical musical instruments being played next to each other will produce a
sound twice as loud as if only one were played.
A hiker shouts "hello" into a canyon and hears it repeated back several times
before it fades away.
The siren of a police car sounds different when the car is coming toward you
than it does when it passes you.

A250-n box is at rest on a frictionless horizotal floor. then a person shoves the box with a non-zero force of magnitude p. which statement best describes the relationship betweeen p and the motion of the box after it was shoved? -the box will not move when p< 250n but otherwise will accelerate at a constant rate that is directly proportional to p - the box will begin moving at a speed that is directly proportional to p, then will gradually slow to a halt -the box will move with constant velocity at a speed that is directly proportional to p -box will accelerate across the floor at a constant rate that is directly proportional to p