particleSystem.Play(); wont start

i wrote this code which i thought should work. the thing is that the particle wont start showing and i cant figure out why. The emitter should emitt for like 2 seconds and then stop.

im guessing that it is because it lies in the void Update function and it starts and stops in a millisecond. but i dont know.

here is the script:

using UnityEngine; using System.Collections;

 public class BloodonHitP1: MonoBehaviour {
 
     public Hit hit;
 
     void Start () {
 
     }
 
     // Update is called once per frame
     void Update () {
     
         if (hit.wonTwo){
 
             particleSystem.Play();
 
         }
     }
 }