Gravity test calculation

GravityTest.cs

using UnityEngine;
using System.Collections;
using UnityTest;
/// <summary>
/// Gravity test.
/// 
/// see formulas here http://error454.com/2013/10/23/platformer-physics-101-and-the-3-fundamental-equations-of-platformers/
/// 
/// d = v*t + 0.5f * a * t * t //d -distance, v - initial velocity, a - aceleration, t - time
/// 
/// for this test v = 0 (initial speed = 0)
/// 
/// d = 0.5f * a * t * t
/// 2d = a * t * t
/// t * t = (2 * d) / a
/// t = sqrt ((2*d) /a )
/// 
/// regarding this link http://www.iforce2d.net/b2dtut/projected-trajectory
/// we have to avoid use timing, and instead of it use frame numbers.
/// also there you can find formula used by box2d
/// p(n) = p0 +n*v + (n2 +n)*a*0.5
/// in our case
/// p(n) = H 	height
/// p(n) = 0 	ground point where our object is falling down
/// v = 0 		start velocity
/// finaly we have folowing formula 
/// n*n + n + 2*H/a = 0
/// </summary>





public class GravityTest : MonoBehaviour {
	public float StartHeight = 1.0f;
	public float FloatEpsilon = 0.05f;

	[HideInInspector]
	public float FallDownTime;

	public int FallDownFrameNumber;
	float startTime;
	int StartFrame;

	FloatComparer timeComparer;
	IntComparer fixedUpdateComparer;
	void Awake(){
		transform.position = new Vector3(0,StartHeight, 0);
		timeComparer = AssertionComponent.Create<FloatComparer>(CheckMethod.OnCollisionEnter2D, gameObject, "GravityTest.FallDownTime", 0.0f);
		timeComparer.floatingPointError = FloatEpsilon;
		timeComparer.compareTypes = FloatComparer.CompareTypes.Equal;


		fixedUpdateComparer = AssertionComponent.Create<IntComparer>(CheckMethod.OnCollisionEnter2D, gameObject, "GravityTest.FallDownFrameNumber", 0);
		fixedUpdateComparer.compareType = IntComparer.CompareType.Equal;
	}
	
	void Start () {
		startTime = Time.timeSinceLevelLoad;	
		float gravityPerFrame =  Physics2D.gravity.y * Time.fixedDeltaTime * Time.fixedDeltaTime;

		float c = 2 * transform.position.y / gravityPerFrame;
		float expectedFixedUpdateNumber = (-1.0f + Mathf.Sqrt(1 - 4 * c))/2.0f;
		timeComparer.ConstValue = expectedFixedUpdateNumber * Time.fixedDeltaTime;
		fixedUpdateComparer.ConstValue = (int)expectedFixedUpdateNumber;

	}
	
	void OnCollisionEnter2D(Collision2D coll) {
		FallDownTime = Time.timeSinceLevelLoad - startTime;
		FallDownFrameNumber = (int)(FallDownTime / Time.fixedDeltaTime);	
	}
}