four cube-shaped blocks are floating in equilibrium in a tank of water. blocks a, b, and c have the same size. block d is larger than the others. the masses of the blocks are unknown.

In the conservation of mass, mass (which is the same as energy) can never be created or destroyed in the same way oil is formed from the remains of small animals and plants that died and fell to the bottom of the sea and their mass (energy) is conserved as oil.

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.