How to make a ball jump?

So far, I’ve been able to move a ball on a 3-dimensional plane using the arrow keys. But I’m not sure how I should make the ball jump. This is the code I have added to the ball to make it move on the plane:

using UnityEngine;
using System.Collections;

public class PlayerController : MonoBehaviour
	public float speed;

	private Rigidbody rb;  

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

	void FixedUpdate()
		float moveHorizontal = Input.GetAxis("Horizontal");
		float moveVertical = Input.GetAxis("Vertical");

		Vector3 movement = new Vector3 (moveHorizontal,0.0f,moveVertical );

		rb.AddForce(movement * speed);


I want to know what I must add to this code in order to make the ball jump.

I do this for my character to move

     if (Input.GetKey("whatever"))
             rb.AddForce(Vector3.up * jumpHeight);

just make a public/private variable named jumpHeight.

If it’s simplicity you’re looking for, this should work:

if (Input.GetKeyDown(KeyCode.Space)
    rb.AddForce(new Vector3(0, 10, 0), ForceMode.Impulse);

This will make the ball jump when you press space. Although I would recommend, you look at the provided standard assets script for controlling Ball; here they are.