The force of attraction between 2 objects is called gravity. why do you think that an object, like your notebook, pulled towards you? explain your reasoning.
i don't need the answer i just don't understand what this question is asking.

The heliocentric and the geocentric models of the solar system included these central principles

What causes the formation of ocean currents?

The atoms in a nickel crystal vibrate as harmonic oscillators with an angular frequency of 2.3 × 1013 rad/s. the mass of a nickel atom is 9.75 × 10-26 kg. what is the difference in energy between adjacent vibrational energy levels of nickel? (h = 6.626 × 10-34 j • s, , 1 ev = 1.60 × 10-19 j)