Ascientist studies the strengths of different types of wood , including oak and maple which of the following is a testable question about this topic ?

Density of salty water as compared to the density of pure water is(a) is less(b) is always equal(c) is always more(d) may be less or more

Two polarizers are oriented at 40∘ to each other and plane-polarized light is incident on them. if only 16 percent of the light gets through both of them, what was the initial polarization direction of the incident light?

What sort of waves exhibit the doppler effect?