Why are the outer or jovian planets considered planets if they are just balls of gas? (this isn't for school, just my own personal research)

The diagram shows a series of volcanic island and a hot spot determine the direction of movement of the tectonic plate that for the island

Which of the following are appropriate acceleration units?

At a certain instant after jumping from the airplane a, a skydiver b is in the position shown and has reached a terminal (constant) speed vb = 52 m/s. the airplane has the same constant speed va = 52 m/s, and after a period of level flight is just beginning to follow the circular path shown of radius ρa = 2330 m. (a) determine the velocity and acceleration of the airplane relative to the skydiver. (b) determine the time rate of change of the speed vr of the airplane and the radius of curvature ρr of its path, both as observed by the nonrotating skydiver.