# Calculating required force for pushing a body to a desired position at once in Unity [duplicate]

In a 3D world I simulate that a coin is being pushed over a plane (applying a force in his rigidbody where y-axis = 0) using a top-down view.

Some time ago but using Box2D, I was able to calculate the amount of force required to stop the coin in a desired position with just one push.

Box2d-js

var fps=60;
var groundFriction = 0.01;
var force= new Box2D.Common.Math.b2Vec2(distance.x * coin.box2dBody.GetMass() * fps * (groundFriction * fps),
distance.y * coin.box2dBody.GetMass()* fps *(groundFriction * fps));
coin.box2dBody.ApplyForce( force, coin.box2dBody.GetWorldCenter(), true );


In order to simulate the friction, during the update, I substracted the groundFriction(0.01) to the linearvelocity of the objects in movement in every frame.

Now using Unity with a more complex physics engine I cant replicate the same.

Unity3d

Vector3 posFinal = transform.position + direction * distFinal;
Vector3 distanceVecFinal = posFinal - transform.position;
float fps= 1/Time.fixedDeltaTime //50 fps
Vector3 force = new Vector3(distanceVecFinal.x  * myBody.mass * fps, 0,
distanceVecFinal.z  *    myBody.mass * fps);


I think that in the final formula I should add the friction of the objects, but I am not sure how to do it. Maybe this is not the only thing that I should change.

I need help pls!

tl&dr Calculate the required force for making move an object to a desired position in a plane with just one push.

• Do you know the standard kinematics equations for motion under a constant acceleration (your friction force) as described in my answer here? gamedev.stackexchange.com/questions/54732/… Jun 3, 2016 at 3:27
• I dont want to do kinematics, I need a full simulation of physics, but thanks. Jun 3, 2016 at 8:09