Now assume that Alice and Bob are twins, and Alice left Earth and Bob stayed behind fixing his spaceship. If Alice spent some time moving near the speed of light before returning to Earth, which statement is correct when Alice returns to Earth?

This is the answer: body 1 + engine 2

Electric force between two charged object varies inversely as the square of distance between them (coulomb's law). this means if two charged objects move away force between them decreases.

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.