PHYSICS: Mechanical Equilibrium “Victor” was my nerd name… Now my name is… “VECTOR!” Let’s review…

PH-YSICS PH-LASHBACK REMEMBER REMEMBER

SCALAR QUANTITY PH-YSICS PH-LASHBACK A scalar quantity is something that does not require a direction. It is a quantity that only has magnitude. Examples of scalar quantities include: Distance… Speed… Time… Mass… Volume… Density… Scalar quantities can be added, subtracted, multiplied, and divided like normal numbers.

Displacement… Velocity… Acceleration… Force… PH-YSICS PH-LASHBACK VECTOR QUANTITY A vector quantity is something that does require a direction. It is a quantity that has both magnitude and direction. Examples of vector quantities include: Displacement… Velocity… Acceleration… Force… Vector quantities cannot necessarily be combined together as easily as scalar quantities.

“Vectors are used to illustrate vector quantities.” Combining Vectors ? ? It’s now time for…the “WELL…DUH” statement of the day. ? ? ? ? “Vectors are used to illustrate vector quantities.” DUH…

Combining Vectors Vectors are handy for illustrating the motion of an object. A vector is an arrow that represents two things: 1) DIRECTION OF MOTION 2) MAGNITUDE OF THE VECTOR The arrow points in the direction of the motion, and the relative length of the arrow gives an indication of the size of the quantity.

Combining Vectors EXAMPLE #1: Bob drives his car 5 miles east and then drives 12 miles west. What is Bob’s displacement? East (+) -12 Resultant -7 or 7 miles W +5

Combining Vectors PHYSICS Vectors are not always that easy… According to GABE …kind of like being Mr. Dillon’s kid…it can be pretty rough… Anyway…in most cases, you cannot just add or subtract! This is where basic trig ideas come into play.

Combining Vectors EXAMPLE #2: Bob drives his car 5 miles north and then drives 12 miles west. What is Bob’s displacement? North/East (+) -12 +5 Resultant 13 miles, 67° W of N

QUESTIONS AND ANSWERS WITH EINSTEIN Q: What are the parts of a vector called? A: The COMPONENTS are the pieces that are combined together to get the resultant. A: The RESULTANT is the final vector that illustrates the motion of the object.

QUESTIONS AND ANSWERS WITH EINSTEIN Q: What are the ways that we work with vectors? A: One situation is when you know the components and you are trying to figure the resultant. A: The other situation is when you know the resultant and you break it into the components.

Rules for Combining Vectors There are two rules that can be used for combining vectors together… RULE #1 – PARALLELOGRAM RULE Put the “tails” of the vectors together and draw the rest of the parallelogram. The resultant is the diagonal of the parallelogram. This rule works good when you have two vectors to work with. It also works well when the vectors that are acting at the same time.

Rules for Combining Vectors There are two rules that can be used for combining vectors together… RULE #2 – HEAD TO TAIL RULE Line the vectors up head to tail. The resultant vector is a vector arrow that connects the starting point and the ending point. This rule works good when you have two or more vectors to work with. It also works well when the vectors that are acting at different times.

Combining Vectors EXAMPLE #3: A plane flies 100 kph east while a tail wind pushes at 25 kph north. What is the resultant velocity of the plane? North/East (+) 103.1 kph, 14° N of E Resultant +25 +25 +100

PHYSICS IS PHUN!