i am making a ball rolling game and i added jumping but for some reason i can jump infinite times

i am making a ball rolling game and i added jumping the the game but for some reason i can jump infinite times here is my code (i put the jump script with the movement script)

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class ballcontroll : MonoBehaviour
{

    public float speed;

    private Rigidbody rb;

    

    void Start()
    {
        rb = GetComponent<Rigidbody>();
    }

    private void FixedUpdate()
    {
        float moveHorizontal = Input.GetAxis("Vertical");
        float moveVertical = Input.GetAxis("Horizontal");
        float jump;
        if (Input.GetKeyDown(KeyCode.Space))
            jump = 14.0f;
        else
            jump = 0;
        Vector3 movement = new Vector3 (moveVertical, jump , moveHorizontal);

        rb.AddForce(movement * speed);
    
    }

}