Unity: distance with addforce

I'm creating a game where you apply a certain force on the block and it walks vertically and has to stop at a certain point and I want to do it for AddForce .

However, on paper, I'm using the formula:

distancia = velocidade ao quadrado/(aceleração vezes coeficiente de atrito) 

And the distance that the object travels gives a different value of this formula. I wanted to resolve this problem.

Comments:

• Drag set to 0 (the angle too).
• The speed of Y also varies when the block moves, even though in AddForce I'm asking only the X position.
• I do not know if it interferes either, but I put the block, on top of the plane, in position 2D (10, -1) and when the game starts, it is pushed to position (-10.00008, -0.9850087 )