An iron nail floats in mercury and sinks in water. Explain why?

To do work, this truck uses energy stored in chemical fuel and an electrical battery. how much total energy does this truck put out?

Dao makes a table to identify the variables used in the equations for centripetal acceleration. what quantities belong in cells x and y?

Ultraviolet radiation is dangerous because it has a high enough energy to damage skin cells. what is the best explanation of the relationship between wavelength and wave energy? a) wave energy is related only to frequency, not wavelength. b) longer wavelengths have lower frequencies but higher energy. c) the shorter the wavelength, the lower the frequency and the higher the energy. d) the shorter the wavelength, the higher the frequency and the higher the energy.