Hey, it's Professor Dave. Let's discuss position, velocity, and acceleration in science. The table Professor Dave explains in physics, we will often be asking questions like "where is an object?", "which way is it moving?", and "how fast?". To discuss the answers to these questions, we will frequently utilize the concepts of position, velocity, and acceleration. So before we go any further, let's define these terms. Position is simple; it's just where an object is in space. Usually, this is discussed with some kind of reference point or axes in mind, and we might express the position of an object as being some distance from this reference point in meters. Velocity is the change in position over time. So, if this object travels five meters in five seconds, it is traveling at a velocity of one meter per second. Acceleration is the change in velocity over time. So, if this object starts at a standstill and over five seconds gradually speeds up to five meters per second, then it is accelerating at one meter per second per second or one meter per second squared. So that's how we define position, velocity, and acceleration. Now let's discuss each of these in more depth. When we talk about position, we could discuss distance or we could discuss displacement. The difference here is that distance is a scalar while displacement is a vector. Let's say you and your friend get dropped off by the school bus at this intersection, and your house is here. Your friend begins to walk down the street and up the driveway like a normal person, but you find yourself so overcome with excitement to play video games that you decide to plow through the yard in a straight line to the door. Your friend has to walk 20 meters down the street and...