* Physical change: A physical change alters the form or appearance of a substance but doesn't change its chemical composition. Examples include melting ice, cutting paper, or crushing a can.

* Chemical change: A chemical change results in a new substance being formed with different properties. Examples include burning wood, cooking an egg, or rusting metal.

When you throw a rock, you are simply changing its position and velocity. You are not changing the rock's chemical makeup. The rock remains the same rock, just in a different location.

Think of it this way:

* The rock's composition (what it's made of) stays the same.

* The rock's state of matter (solid) stays the same.

* Only the rock's position and motion change.

So, throwing a rock is a change in motion, not a physical change.