CoinsController.cs

/* CoinsController.cs */
using System.Collections.Generic;
using UnityEngine;

public class CoinsController : MonoBehaviour
{
    [SerializeField]
    private int numberOfCoins;

    [SerializeField]
    private float radius;

    [SerializeField]
    private string coinTag;

    [SerializeField]
    private float pickupSpeed;

    [SerializeField]
    private float pickupDistance;

    private List<Transform> coins;

    void Start()
    {
        coins = new List<Transform>();
    }

    void FixedUpdate()
    {
        Collider[] hitColliders = Physics.OverlapSphere(transform.position, radius);

        for (int i = 0; i < hitColliders.Length; i++)
        {
            if (hitColliders[i].CompareTag(coinTag) &&
                !coins.Contains(hitColliders[i].transform))
            {
                coins.Add(hitColliders[i].transform);
            }
        }

        for (int i = 0; i < coins.Count; i++)
        {
            if (Vector3.Distance(transform.position, coins[i].position) <= pickupDistance)
            {
                numberOfCoins += 1;
                coins[i].gameObject.SetActive(false);
                coins.Remove(coins[i]);
            } 
            else
            {
                float step = pickupSpeed * Time.deltaTime;
                coins[i].position = Vector3.MoveTowards(coins[i].position, transform.position, step);
            }
        }
    }
}

/* Movement.cs */
using UnityEngine;

public class Movement : MonoBehaviour
{
    private new Rigidbody rigidbody;

    [SerializeField]
    private float speed;

    [SerializeField]
    private ForceMode forceMode;

    // Start is called before the first frame update
    void Start()
    {
        rigidbody = GetComponent<Rigidbody>();
    }

    // Update is called once per frame
    void Update()
    {
        float h = Input.GetAxis("Horizontal");
        float v = Input.GetAxis("Vertical");
        Vector3 velocity = new Vector3(0, 0, v);
        velocity = transform.TransformDirection(velocity);
        velocity *= speed;
        velocity -= rigidbody.velocity;
        rigidbody.AddForce(velocity, forceMode);
        transform.Rotate(new Vector3(0, h, 0));
    }
}