* Gravity: The primary force acting on the rock is gravity, which pulls it downwards.
* Initial Upward Velocity: When the rock is thrown upwards, it has an initial upward velocity.
* Deceleration: Gravity constantly opposes this upward velocity, causing the rock to slow down as it rises.
* Zero Vertical Velocity: At the highest point of its trajectory, the rock momentarily has zero vertical velocity before it begins to fall back down.
Think of it like throwing a ball straight up in the air. It slows down as it goes up, stops for a split second at the top, and then speeds up as it falls back down.
