How can I get my trampoline script to work? - unity3d

Question

So I'm making a puzzle based game in which the player must use Trampolines which detect when the player jumps on top of it and bounces them up x amount of height.
However currently at the moment my code isn't working and stating error that
"Cannot modify the return value of 'UnityEngine.Rigidbody.velocity' because it is not a variable."
Wondering if any you guys know what could be done to fix this code and allow it to work to the purpose its needed for.
using UnityEngine;
using System.Collections;
public class small_trampoline_bounce : MonoBehaviour {
bool willBounce = false;
float bounceHeight = 10;
public Transform Player;
// Use this for initialization
void Start ()
{
}
// Update is called once per frame
void Update ()
{
if (willBounce)
{
Player.rigidbody.velocity.y = 0;
Player.rigidbody.AddForce (0, bounceHeight, 0, ForceMode.Impulse);
willBounce = false;
}
}
void OnCollisionEnter (Collision other)
{
if (other.gameObject.name == "Player")
{
willBounce = true;
}
}
}

Answer 1

To address the specific error you are getting - since velocity is a vector, you can't modify the returned vector and expect the stored vector to change. If you really want to set the velocity directly, you need to set the whole vector, not just a portion:
Player.rigidbody.velocity = new Vector3(0, 0, 0);
If you want to maintain previous x and z velocity, you can do this:
vector3 velocity = Player.rigidbody.velocity;
Player.rigidbody.velocity = new Vector3(velocity.x, 0, velocity.z);