When a bullet is fired from a gun, what is true about the momentum?
the gun has more momentum than the bullet, so the momentum is not conserved.
the bullet and gun have equal momenta in opposite directions, so the system's momentum is conserved.
the bullet has more momentum than the gun, so the momentum is not conserved.
the bullet and the gun have equal momenta in the same direction, so the system's momentum is conserved.

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.