Final answer:
The two balls thrown by Janelle have the same acceleration due to gravity and the same initial velocity but may not have the same final velocity or displacement due to their different initial directions of motion.
Step-by-step explanation:
The question is about the motion of two balls thrown by Janelle, one straight up and one straight down, as observed by Michael from a balcony. In an ideal scenario without air resistance, both balls are subject to the same acceleration due to gravity, which is independent of the initial direction of motion. So, point 1) Both balls have the same acceleration is correct. Point 3) Both balls have the same initial velocity is also true because Janelle throws them with the same initial speed, regardless of the direction.
However, point 2) Both balls have the same final velocity is not necessarily true, as the ball thrown downwards will have the initial speed and the speed gained due to gravity, while the ball thrown upwards will have to come to a stop before it starts to fall back down. Point 4) Both balls have the same displacement is also incorrect, as their starting points are different; one starts from a higher point when thrown upwards, and the other from a lower point when thrown downwards.
In summary, gravity affects both balls equally and their vertical motions are independent of the horizontal aspects. For ideal conditions, without air resistance, vertical acceleration is constant, and any initial horizontal velocity would remain unchanged as there are no horizontal forces acting on the balls after they are thrown.