Rigidbody

using UnityEngine;

public class PhysicsPlayer : MonoBehaviour
{
  [SerializeField] private float moveForce = 10f;
  [SerializeField] private float jumpForce = 7f;
  [SerializeField] private float maxSpeed  = 8f;
  private Rigidbody _rb;
  private Vector3   _input;
  private bool      _grounded;

  void Awake() => _rb = GetComponent<Rigidbody>();

  void Update()
  {
      _input = new Vector3(Input.GetAxisRaw("Horizontal"), 0,
                           Input.GetAxisRaw("Vertical"));
      if (Input.GetButtonDown("Jump") && _grounded)
          _rb.AddForce(Vector3.up * jumpForce, ForceMode.Impulse);
  }

  void FixedUpdate()
  {
      // Cap speed on the horizontal plane
      Vector3 flatVel = new Vector3(_rb.velocity.x, 0f, _rb.velocity.z);
      if (flatVel.magnitude > maxSpeed)
          _rb.velocity = flatVel.normalized * maxSpeed + Vector3.up * _rb.velocity.y;

      _rb.AddForce(_input.normalized * moveForce, ForceMode.Force);
  }

  private void OnCollisionEnter(Collision col)
      => _grounded = col.gameObject.CompareTag("Ground");

  private void OnCollisionExit(Collision col)
      => _grounded = false;
}

using UnityEngine;

public class Explosion : MonoBehaviour
{
  [SerializeField] private float force     = 500f;
  [SerializeField] private float radius    = 5f;
  [SerializeField] private float upModifier = 0.5f;

  public void Explode()
  {
      // Find every Collider inside the radius
      Collider[] cols = Physics.OverlapSphere(transform.position, radius);

      foreach (var col in cols)
      {
          var rb = col.GetComponent<Rigidbody>();
          if (rb == null) continue;

          // Unity scales the force by distance
          rb.AddExplosionForce(force, transform.position, radius, upModifier);
      }

      // Visual effect + destroy
      GetComponent<ParticleSystem>()?.Play();
      Destroy(gameObject, 2f);
  }
}