A 2000 kg tractor, starts at the bottom of a 50. m mountain while traveling at 45 m/s. During the trip, air resistance does -100 kJ of work on the tractor, and friction does an additional -550 kJ of the work. What is the minimum amount of work the engine must do in order for the tractor to reach the top?

No it would not hope that

It is increased due to the doppler effect. (apex)

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.