This topic is in the 'Motion Problems with Acceleration' section. When the speed or direction of an object changes, then that object accelerates, and the ideas that follow are what this section is all about. Instead of just one 'distance equals speed times time' equation, we now get a whole of bunch of equations that relate acceleration, displacement, initial velocity, final velocity, and time. Each equation that you'll learn about is missing one of those 5 variables, and checking which variable is missing is a great way of keeping the equations straight. There are many variations to problems involving these variables, and you'll see a bunch in the tutorials for this section!