 In this video, I'm going to be looking at the main equation for constant acceleration, which is that the position as a function of time is the initial position plus initial velocity times time plus one half acceleration times time script. Now, especially if you talk about 2D kinematics, you have to consider that this is a vector equation. You have positions as vector, velocity as vector, and acceleration as vector. Now, why is this the main equation? Because you can get all the other equations from it. You know that the velocity as a function of time is the derivation of the position. So the user function of time is ds over dt. So if I derive this, my initial position falls out. And I have here v initial plus 2 times one half is the acceleration times time. Then all the other five equations are just combinations or variants of this one here. What is interesting in 2D motion is that what happens in x direction, what happens in y direction, is completely independent, meaning you can rewrite this as a x equation or a y equation as an x equation. I can say that I have the position as a function of the position in x is x initial plus v x initial times time plus one half acceleration x t squared. And in y, I have the same thing as y as a function of time is v s y initial plus v y initial times time plus one half a y t squared.