Go to the To Scale tab at the bottom of the simulation, and select Path from the central menu on the right. Set up a Planet-Moon simulation. Use the sliders to make both the planet and the moon as massive as possible, and then begin the simulation. What do you notice about the moon’s motion when it is closest to the planet? What about when it is farthest away?

Go to the To Scale tab at the bottom of the simulation, and select Path from the central menu on the right. Set up a Planet-Moon simulation. Use the sliders to make both the planet and the moon as massive as possible, and then ... What do you notice about the moon's motion when it is closest to the planet?

Explanation:

the density(ratio between mass and volume as m/v) decreases from top to bottom in periodic table group as the size increases and nuclear charge decreases. but in periods density increases from left to right as atom size decreases and nuclear charge increases.

the answer to this question is 3.