int n = 0;
Rigidbody rb = null;

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

private void Update()
{
if(n == 0)
{
rb.velocity = Vector3.zero;  
rb.angularVelocity = Vector3.zero;
var v = new Vector3(0, 0, 200.0f);
rb.AddForce(v);
}

n++;
if(n == 2500)
{
rb.velocity = Vector3.zero;
rb.angularVelocity = Vector3.zero;
var v = new Vector3(0, 1.0f, -200.0f);
n = -2500;
rb.AddForce(v);
}
}