Randomness of Unity physics?

Question

Unity

When I press W the character jumps, but each time to a different height, how to fix it?

void Update()
         {
             Jump();
         }
     
     private void Jump()
         {
             if (Input.GetKeyDown(KeyCode.W))
             {
                 
                 var jumpVel = new Vector2(0, jumpForce * Time.deltaTime);
                 rb.velocity += jumpVel;
                 
             }
         }

Answer 1

Basically just do it

void FixedUpdate()
         {
             Jump();
         }
     
     private void Jump()
         {
             if (Input.GetKeyDown(KeyCode.W))
             {
                 
                 var jumpVel = new Vector2(0, jumpForce);
                 rb.velocity += jumpVel;
                 
             }
         }

Answer 2

1) Time.deltaTimehas a different meaning each time.
2)

var jumpVel = new Vector2(0, jumpForce * Time.deltaTime);

- you are trying to add speed instead of strength.
3) rb.velocity += jumpVel;- you add speed, so the sum can be at least zero. I recommend setting the speed hard: rb.velocity = jumpVel;