Only able to jump when grounded.,Only doing something if something is true

Questions & Answers
1

IsGrounded.cs
{
public bool grounded = false;

void OnCollisionEnter2D (Collision2D collisionGround)
{
    if (collisionGround.collider.tag == "Ground")
    {
        grounded = true;
    } else
        {
            grounded = false;
        }
        
}

Movement.cs

void FixedUpdate()
{
if (grounded == true)
{
if(Input.GetKey(“Space”))
{
rb.AddForce(new Vector2(0, jumpSpeed * Time.deltaTime), ForceMode2D.Impulse);
}

2

How I usually do it in my games:

public bool CheckGroundProximity()
{
isGrounded = false;

    Ray ray = new Ray(transform.position, Vector3.down);

    if (Physics.Raycast(ray, 0.25f, LayerMask.GetMask("Terrain", "Walkable"))){
        isGrounded = true;          
    }
    return isGrounded;
}

Raycasts a certain distance down from your players position and if it hits a ground collider on the layer “Terrain” or Walkable then return true. In your if it should be:

if (CheckGroundProximity() == true)
{
Code Here
}