4A: With every beat, your heart pumps blood throughout the vessels of your body. Let’s look at the radial artery, one of the vessels in your arm. How fast is the blood going at a particular point in time, and in what direction? The speed is an absolute number without direction - 1.8 kilometers per hour in this case. Velocity expands on the speed, which is an absolute value, by adding direction - for instance, 1.8 kilometers per hour downward. It’s that easy! you already grasping the concept of speed and velocity, terms used to describe the rate of change in our distance over time.