Suppose astronomers find an earthlike planet that is twice the size of earth (that is, its radius is twice the radius of earth). what must be the mass of this planet such that the gravitational force (fgravity) at the surface would be identical to earth's?

Sawyer is studying diffraction. he draws a diagram of a plane wave to show how light waves travel. which best describes sawyer’s error? the wave fronts should be perpendicular to the direction in which the waves move. the arrow showing the direction of movement of the waves should be pointing to the left. the arrow showing the direction of movement of the waves should be pointing downward. the wave fronts should be both parallel and perpendicular to the direction in which the waves move.