If Kofi is standing at the bottom of a hill and Chiara is standing halfway up the hill, each of them with a ball in their hand, and they both let go of the balls at the same time, what happens to the balls and what can each person see with regard to the other person's ball? Provide a very brief response.
When Kofi and Chiara let go of their balls, gravity will cause both balls to roll downhill. Chiara, being higher on the hill, will be able to see Kofi's ball rolling down towards him, as her elevated position gives her a clear line of sight to Kofi and his ball. However, Kofi may not be able to see Chiara's ball roll immediately, because the slope of the hill may obscure his line of sight, depending on the steepness of the hill and his distance from where Chiara is standing. As Chiara's ball rolls further down the hill, it will eventually come into Kofi's line of sight as long as there are no other obstructions on the hill.