Hello! I made this little graphic with an animation from the past to show you how weight affects speed on your animation.
Red parts show a strong weight/ slow speed while blue parts show light weight/ more speed.
Generally speed comes when the item flows in the air, going faster just before landing, also sliding, the more it slides, the faster it goes. Don't hesitate to use smears to accentuate the effect if needed :)
Hope this little explanation can help, l should decorticate more of my old animations to show you example of principles ^^