As a killer whale swims toward a seal, it sends out sound waves to determine the direction the seal is moving. When the
frequency of the reflected waves increases, the whale is(n)
the seal
A. catching up to
B. falling behind

Ithink it is a. but i'm not 100 percent sure.

C. hope this . : )

Jenny and fred both play a long note on their trombones. a stationary observer hears the sound increasing and decreasing repeatedly in loudness. which of these must be true? the sound waves from the two trombones have slightly different frequencies.the sound waves from the two trombones have the same frequency.the sound waves from the two trombones have slightly different amplitudes.the sound waves from the two trombones have the same wavelength.the sound waves from the two trombones have slightly different velocities.  lolthe answer is          the sound waves from the two trombones have slightly different frequencies.