Mine

if (prevState != null)
{
    DateTime currentTime = DateTime.Now;

    TimeSpan timeDelta = currentTime - lastTime;

    float velocity = timeDelta.Milliseconds / state.AccelState.X;
    float accel = velocity / timeDelta.Milliseconds;
    float force = 10 * accel;
    Console.WriteLine("F: {0}\t\t T:{1}", force, timeDelta.ToString());
           
}

prevState = state;