Speed is equal to, if you're thinking about it in one dimension, you could think about it as the absolute value of your velocity as a function of time, or your magnitude of velocity as a function of time. So in the beginning, even though your velocity is becoming more and more negative, your speed is actually increasing. Your speed is increasing to the left, then your speed is decreasing, you slow down, and then your speed is increasing as we go to the right. And we'll do some worked examples that work through that a little bit more. Now, the last concept we will touch on in this video is the idea of acceleration. And acceleration, you could view as the rate of change of velocity with respect to time. So acceleration as a function of time is just going to be the first derivative of velocity with respect to time, which is equal to the second derivative of position with respect to time.