let particleX = 150
let particleY = 50
let dy = 0
function setup() {
createCanvas(windowWidth, windowHeight)
}
function draw() {
particleY += dy
dy += 0.5
fill("darkblue")
rect(0, 0, width, height)
fill("white")
rect(particleX, particleY, 10, 10)
}