In our usual coordinate system( +x to the right, +y up (away from the center of the Earth), +z out of the page toward you), what
is the vector gravitational force on a 31 kg object sitting on the ground? (From the momentum principle you can conclude that a force of the same magnitude is exerted upward by the ground on the object if the momentum isn't changing. In Chapter 4 we'll see more about the origin of this force.)
The rock it traveling really, really fast. It is hard to exactly determine how fast bc u need the height of the cliff and how big the rock is. Hope this helps and can I get brainliest answer!