Brilliant! The ball starts from a y co-ordinate of $$10$$ and then falls to the ground, which has a y co-ordinate of $$0$$. So, the displacement is $$0-10 = -10$$
It is very important to remember that displacement means you must calculate $$\text{Final position}$$ $$- \text{Initial Position}$$. Many students calculate $$\text{Initial Position}$$ $$- \text{Final position}$$ and get the opposite sign.
What is the displacement of the ball in the case of this animation? Assume the ball is initially dropped from $$y=10$$
• $$10$$
• $$-10$$
• $$0$$
• $$20$$