Here is the link to my assignment.
Basically I created an apple tree along a river. I used basic shapes in p5 and created the outlines first. For the apples, I used the particle classes and applied according forces to them.
As the mouse is pressed, an apple in the tree will fall down with gravity. And at the same time, there will be a new apple appearing in the tree.
When the apples fall into the water, there will be another force in the water and the resistance is also different from that in the air. The force in the water is controlled by mouse position and can be manipulated by the user.