What is the purpose of a reference point?

If a balloon is taken outside on a very cold day, what will occur?

If the new moon happens on january 15th, what shape will it be on february 6th?

Greg drew a diagram to compare two of the fundamental forces. which labels belong in the areas marked x, y and z? gravitational force electromagnetic force x. attractive y repulsive z: infinite range x: infinite range y attractive z. repulsive x. always attractive y: infinite range z: attractive or repulsive x. attractive or repulsive y infinite range z: always attractive