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# 1: Motion

• 1.1: Vectors
Just being able to put numbers on physical quantities is not sufficient for describing nature. Very often physical quantities have directions. We give such quantities that have directions attached to them the generic name of vector.
• 1.2: Vector Multiplication
Now we know how to do some math with vectors, and the question arises, “If we can add and subtract vectors, can we also multiply them?” The answer is yes and no. It turns out that there is not one unique way to define a product of two vectors, but instead there are two…
• 1.3: Straight-Line Motion
There is nothing more fundamental in the study of physics than motion. We will bring a lot of mathematics to bear on this subject (including the vectors we just learned about), but we are going to start as easy as possible – with motion that remains on a straight line.
• 1.4: Kinematics
Okay, enough of the definitions. Let’s see how these things all fit together, and how they can be used. What we will be looking at are called the equations of motion, and this topic is often referred to as kinematics.
• 1.5: Graphing
We conclude our discussion of straight-line motion by taking on the topic of representing motion with graphs.
• 1.6: Motion in Multiple Dimensions
Now that we have mastered the simplest form of motion, it’s time to branch out to more general cases. No longer will the motion of objects be constrained to move along a straight line! Of course, this means that we can no longer allow simple positive and negative values to tell us about directions – we need to introduce vectors into the story.
• 1.7: Examples of 2-Dimensional Motion
Using what we just derived regarding the parallel and perpendicular components of acceleration, we turn now to the special cases of circular and projectile motion.
• 1.8: Relative Motion
Our last topic for motion in multiple dimensions relates what different observers of the same motion measure for velocities.