How do the characteristics of the planets, moons, and smaller objects in the solar system compare?

What is the magnitude of the resultant vector round your answer to the nearest tenth

The period of a pendulum varies directly as the square root of the length of the pendulum and inversely as the square root of the acceleration due to gravity. find the period when the length is 144 cm and the acceleration due to gravity is 980 cm per second squared, if the period is 7pi seconds when the length is 289 cm and the acceleration due to gravity is 980 cm per second squared.

If the area of a square has increased by a factor of 16, by how much has each side increased?