What is electricity a) the movement of molecules b) the movement of atoms c) the movement of circuits d) the movement of electrons

What is the relationship between the wavelength of a wave and it's energy?

Automobile fuel efficiency is often measured in miles that the car can be driven per gallon of fuel (mpg). heavier cars tend to have lower fuel efficiencies (lower mpg ratings). which variable (weight or fuel efficiency) is most naturally considered the explanatory (predictor) variable in this context?

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.