SIMPLIFIED: "2.1: Basics of Kinematics"

Article Link: https://phys.libretexts.org/Bookshelves/University_Physics/Physics_(Boundless)/2%3A_Kinematics/2.1%3A_Basics_of_Kinematics 

Note: The image above was taken from the original article.

This article introduces readers to kinematics. Kinematics is essentially the study of motion, which includes an object’s position, velocity, and acceleration. Kinematics excludes the study of what is changing an object’s motion, meaning MOST forces are excluded from the study of kinematics (with the exception of the force of gravity). 

The article first introduces readers to the concept of displacement. Displacement, simply put, is the change in position of an object. For instance, let’s say an object first starts at x=0. If the object moves 10 units to the right, then the displacement is 10 units, because the change in position is 10 units to the right. The formula for displacement is as follows: displacement = (final position) - (initial position). Remember: displacement and the distance an object has traveled are NOT the same thing. An object can move 5 units to the right, and then move 5 units back to the left. The total distance the object has traveled would be 10 units in this case, but the displacement is 0, because the change in position is 0. 

The article next mentions scalars vs. vectors. Here is the simple difference: scalars do not have direction, but vectors do. Here is an example: speed is a scalar, while velocity is a vector. For example, you might say that a car’s speed is 10 miles per hour. However, that car’s velocity would need to include its direction, such as saying “the car’s velocity is 10 miles per hour to the right”. You can notice that when expressing an object’s velocity, you need to include the direction, because velocity is a vector. When solving kinematics questions or doing physics problems, you can generally just put a positive sign (+) next to a number to represent that the object is moving to the right and a negative sign (-) next to a number to indicate that the object is moving to the left.