Im confused on why you want to add force based on the angle of the floor? Wouldn’t you want to add force in the forward direction of the sled. The sled will angle at the same angle of the floor its on, so you want force in its current forward angle. (Which should be the X). So you would want to use “get forward vector” on the sled (or character).
If you needed to make the sled “stick” to the angle of the floor then you could do a downward line trace to get the hit normal then multiply that by a negative number that feeds into an apply impulse node on the sled.