How would I make a part face its front where its falling to?

I am making a custom particle system with collisons, and the particle image will be inside the part thats falling, so I want to raycast from its front to where its falling to, so I need to make the front of it face where its falling to. Heres an image of what i want to achieve:

this example is 2d but I need to achieve this in 3d of course