What unit of length is used to express the size of stars?

Apebble is thrown into a calm lake, ripples are formed from the center and move outward. the water particles in the lake travel in a circular pattern that moves up and down on the surface of a lake, and the energy travels a) diagonally. b) downward. c) horizontally. d) upward.

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.