Collision in between 2 objects moving away from each other?

I have a cube and a terrain in which the cube is moving away from the terrain at a regular pace . what i need is to enable gravity for any object that comes in between both of the objects(terrain & cube),much like an extensible collider .Is there any way to implement this using colliders or other stuff.thanks in advance.

You can use a CapsuleCastAll.

[CapsuleCastAll][1]

Essentially, it’s a Capsulecast that stores all colliders within the Cast in an array. So you’ll have to call it every update and specify where it starts and ends. Like so:

//Get distance of cube from floor
var distance : float = Vector3.Distance(cube.position,floor.position);
var hits : RaycastHit[];
hits = Physics.CapsuleCastAll (cube.position, cube.down * distance, 1.0, cube.down, distance);

for (var i = 0; i < hits.Length; i++) {
      //Apply Gravity;
      hits_.rigidbody.AddForce(Vector3.down * Physics.gravity);_

}
[1]: Unity - Scripting API: Physics.CapsuleCastAll