Select the correct answer.
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?
A. The sound waves from the two trombones have slightly different frequencies.
B. The sound waves from the two trombones have the same frequency
C. The sound waves from the two trombones have slightly different amplitudes.
D.
The sound waves from the two trombones have the same wavelength,
E.
The sound waves from the two trombones have slightly different velocities.

Two manned satellites approaching one another at a relative speed of 0.550 m/s intend to dock. the first has a mass of 2.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. assume that the positive direction is directed from the second satellite towards the first satellite. (a) calculate the final velocity after docking, in the frame of reference in which the first satellite was originally at rest.(b) what is the loss of kinetic energy in this inelastic collision? (c) repeat both parts, in the frame of reference in which the second satellite was originally at rest. final velocity(d) loss of kinetic energy = ?