如何在FixedUpdate中移动刚体，但角色仍受重力影响？

using UnityEngine;

public class CharacterController : MonoBehaviour
{
    public float moveSpeed = 5f;
    private Rigidbody2D rb;

    private void Start()
    {
        rb = GetComponent<Rigidbody2D>();
    }

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

        Vector2 movement = new Vector2(moveHorizontal, moveVertical);
        rb.AddForce(movement * moveSpeed);
    }
}