Here's the breakdown:
* Speed is a scalar quantity: It only tells you how fast something is moving, not the direction. Speed is always a positive number.
* Velocity is a vector quantity: It tells you both how fast something is moving *and* in what direction. Velocity can be positive or negative depending on the chosen coordinate system.
So, to answer your question:
* Speed: The speed of the ball is always positive as it falls back to Earth. It's simply how fast the ball is moving.
* Velocity: The velocity of the ball can be considered negative if you define "downward" as the negative direction in your coordinate system.
Think of it this way: Imagine a ball thrown straight up. As it rises, its velocity is positive (moving upward). As it reaches the peak and starts falling, its velocity becomes negative (moving downward). However, its speed remains positive throughout the entire journey.
Let me know if you have any other physics questions!
