Play sound on collision + change colour based on velocity

PlaySoundOnCollision.cs

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

public class PlaySoundOnCollision : MonoBehaviour
{
    public AudioSource mySound;
    public Rigidbody2D rb;
    float velocityMag;
    public Gradient myColour;

    private void Update()
    {
        velocityMag = rb.velocity.magnitude/10;
        GetComponent<SpriteRenderer>().color = myColour.Evaluate(velocityMag);
    }


    private void OnCollisionEnter2D(Collision2D collision)
    {
        mySound.pitch = rb.velocity.magnitude;
        mySound.Play();
    }
}