大家都知道物体移动需要遵循物理原则，那怎么实现这一功能呢？
加上刚体，通过代码来达到按键控制的目的

public GameObject obj;
    public Rigidbody r;
    private void Start()
    {
        obj = GameObject.Find("Cube");
        r = obj.GetComponent<Rigidbody>();
    }
    private void Update()
    {
         if (Input.GetKey(KeyCode.UpArrow))
        {
            r.AddForce(new Vector3(0, 0, 10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.W))
        {
            r.AddForce(new Vector3(0, 0, 10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.DownArrow))
        {
            r.AddForce(new Vector3(0, 0, -10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.S))
        {
            r.AddForce(new Vector3(0, 0, -10), ForceMode.Force);        }
        if (Input.GetKey(KeyCode.A))
        {
            r.AddForce(new Vector3(-10, 0, 0), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.LeftArrow))
        {
            r.AddForce(new Vector3(-10, 0, 0), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.D))
        {
            r.AddForce(new Vector3(10, 0, 0), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.RightArrow))
        {
            r.AddForce(new Vector3(10, 0, 0), ForceMode.Force);
        }
        if (Input .GetKeyDown(KeyCode.Space))
        {
            r.AddForce(new Vector3(0, 10, 0),ForceMode.VelocityChange);
        }
    }

[RequireComponent(typeof(Rigidbody))]//必须有刚体
public class putint : MonoBehaviour
{
    public GameObject obj;
    private void Start()
    {
        obj = GameObject.Find("Cube");
        r = obj.GetComponent<Rigidbody>();
    }
    private void Update()
    {
        if (Input.GetKey(KeyCode.UpArrow))
        {
            r.AddForce(new Vector3(0, 0, 10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.W))
        {
            r.AddForce(new Vector3(0, 0, 10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.DownArrow))
        {
            r.AddForce(new Vector3(0, 0, -10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.S))
        {
            r.AddForce(new Vector3(0, 0, -10), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.A))
        {
            r.AddForce(new Vector3(-10, 0, 0), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.LeftArrow))
        {
            r.AddForce(new Vector3(-10, 0, 0), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.D))
        {
            r.AddForce(new Vector3(10, 0, 0), ForceMode.Force);
        }
        if (Input.GetKey(KeyCode.RightArrow))
        {
            r.AddForce(new Vector3(10, 0, 0), ForceMode.Force);
        }
        if (Input .GetKeyDown(KeyCode.Space))
        {
            r.AddForce(new Vector3(0, 10, 0),ForceMode.VelocityChange);
        }
    }
}