Vectors may be hard to understand to many physics students. Personally, it took me about a month to finally have a grasp on what exactly a vector was or did.
First a scaler quantity has a measure of just magnitude. A vector quantity has both magnitude and direction. A scaler quantity is just 3m/s x 3m/s = 9m/s. Vectors use a different sort of symbols and how they are measured.
Lets say we have a car moving at 30 m/s at 0 degrees north. The vector would point to the top of the page and the symbol for the vector would be an A with an arrow over the A. Now when you have two vectors pointed the same and have the same magnitude this referred to as "Parallel Vectors." Now when we have two vectors moving opposite directions, this is called negative vectors. The symbol for negative vectors is A=-B or -B=A. We refer to this as antiparallel.
We must remember the the magnitude of a vector quantity is always positive. Drawing vectors is like drawing a scale for a map. Lets say 1 centimeter drawn equals 9 km and 2 cm's equals 18 km. So you must draw a scale when you draw your vector.
Vector Addition and Subtraction
Another simple but tough area of physics to grasp. Remember this equation C=B+A. This looks like Pythagorean's theorem doesn't it? Well this is somewhat similar. C is the hypotenuse of our equation and B+A are the arrows that add for C. However, this does not at all mean the magnitudes are the same. The magnitudes depend on the angle of the two vectors and the magnitudes of those two vectors. Also if the vectors are opposites of each other then we subtract the two vectors.
Next lesson will be tomorrow July 10th
Questions email me at mjacks66@msudenver.edu
Mark Jackson
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