adding speed make the ball bounce

okay so I’m using this script for my ball to move with the accelerometer but when I add the speed it starts to bounce like crazy
to be specific when I add “transform.Translate” line that happens I’m still new to this any help will appreciate it

using UnityEngine;
using System.Collections;

public class Accelerometer : MonoBehaviour 
	public float speed = 5.0F;
	public bool isflat = true;
	private Rigidbody rb;

	void Start()

		rb = GetComponent<Rigidbody> ();

	void Update()

		Vector3 tilt = Input.acceleration;
		if (isflat)
			tilt = Quaternion.Euler (90, 0, 0) * tilt;

		transform.Translate(tilt * speed * Time.deltaTime);

You shouldn’t use transform.Translate and rb.AddForce at once. If your object is physic to move it you should use only Rigidbody without modifying transform. It is also good practice to do all physic calculations in FixedUpdate.