The speed of a sound wave changes from 6,100 m/s to 1,484 m/s and then to 344 m/s as it passes through different materials. Which of the following sequences could produce these changes in speed?

Air, water, steel.
Steel, water, air.
Steel, air, water.
Water, steel, air.

What happens to light waves from a star as the star moves away from earth?

In a given chemical reaction, the energy of the products is greater than the energy of the reactants. which statement is true for this reaction?

Starting with only the balmer series light (visible light), how could we ensure that the solar panels generate a current that mark can use for his power station? a)by gradually increasing the brightness (amount) of light that we shine on it. b)by gradually increasing the frequency of the light we shine on it. c)by gradually increasing the wavelength of the light that we shine on it.