Why can't the teacher test the amount of water and the amount of sunlight in the same experiment? The plants would not grow At t
he end, he would not know which caused the plants to grow differently The plants would grow too fast Actually, he can test both things in the same experiment
Within the system of the same star, the period of a planet's orbit is proportional to the 3/2 power of its distance from the central body. (Kepler's empirical third law of planetary motion, promoted to being etched in stone by Newton's gravitation.)
