How can you make a platfrom fall when the character walks/jumps on it?

How can I make a platfrom fall when the character walks/jumps on it?

Create a platform with a collider and a rigidbody on it, and turn off gravity for the platform. Add an event for OnCollisionEnter() onto the platform. When the player touches and collides with the platform, call rigidbody.useGravity = true; to turn on gravity, thus, making the platform fall down.

Everything that is in bold, you can look up in the Unity Script Reference to learn how to use.

#pragma strict

function OnCollisionEnter(Char){
	rigidbody.useGravity = true;
}

I’ve tried dis one ( function OncollisionEnter ( player ) { Rigidbody . Use Gravity = true; } and it works but the problem is that my player barely stay on the platform cuz it falls really fast I tried to active the collision but wen I do that d script doesnt work.