Does anyone know how could i get an entity velocity?

I'm trying to predict whenever an item entity (literally a dropped item with a huge pickup delay) hits a block (it can be a roof, a wall or the floor). To do this i tought to get the current velocity of my entity and add it to it's position 'predicting' where the entity will be in the next tick.
i saw there is a Motion nbt tag but i don't understand if that is the current velocity or just the initial one, thanks for the help