10-31-11
Agenda
HOMEWORK CHECK
Place on your desk:
*Calculator & Protractor
*Orange Homework Chart
*Protractor/Angle Packet (graph paper)
 1) Vector components in a right triangle
θ
are named relative to____.
1) Warm-Up
5 min
2) Finish Vocab. Words 10 min
3) Vocab. Quiz 15 min
4) Vector fill-in notes 15 min
5) Examples of Fnet 15 min
6) “In the Park” worksheet 15 min
7) Physics Test Review 20 min
 2) The process of resolving a vector into
resolution
its components is called____________.
8) Pre-Vector Worksheet II
Vocab.
1. Equilibrant: the one force that brings the net force to
equal zero. The equilibrant is equal to but opposite the
resultant.
2. Graphical Representation: using a vector diagram to
represent either forces acting on an object or velocity/
acceleration vectors.
Review:
-Vectors requite magnitude (how much) and direction & or
orientation.
-Scalar quantities (speed, time, mass, etc) do not require
direction but do have magnitude.
-Direction of vectors on paper: top of page is NORTH,
bottom of the page is SOUTH, to the right is EAST and the
left is WEST OR A COMBINATION.
-Types of vectors which have been studied and will be
covered in this unit:
•Weight vectors which are always drawn 90˚ from the
middle of the object which has the weight.
•Friction vectors will be drawn horizontal OR against the
other force that is acting AGAINST
•Force vectors are drawn based on the NET FORCE which
will cause the motion.
•Velocity vectors are drawn exactly as any force vectors but
2 terms are used:
-Tailwind which means the wind is from behind or also
moving in the same direction.
-Headwind means head-on so that the object is moving
against the direction; opposite direction.
-Relative to the ground= horizontal direction and can
also be used with an angle that is “relative to the ground.
PARTS OF A VECTOR:
-Component & or composition of vectors: finding the
diagonal.
[resultant/diagonal/hypotenuse or NET FORCE of the 2
quantities given] which will form the right triangle.
Component vectors are the horizontal and vertical vectors
which make the 2 sides of the triangle. The unknown angle
called theta is used to find the diagonal based on where the
angle is located.
-Resolution of vectors: the diagonal is known and you
“resolve” the diagonal to find the 2 sides of the triangle
based on the given angle (theta).
METHODS USED TO SOLVE FOR VECTORS:
•GRAPHIC METHOD: the horizontal and vertical lines are
drawn to scale and the hypotenuse is solved by
measurement based on the scale.
•Trig. Functions: Use of sine, cosine and tangent
•Parallelogram Method: 4 sided shape in which the opposite
sides are parallel and equal in length—the resultant is the
diagonal of the parallelogram—used with the graphic and
Trig method.
Pythagorean theorem: A2+B2=C2 **Can ONLY be used when
“direction” is not an issue---so, NOT with Vectors!!!
EQUILIBRIUM VECTORS– When forces are opposite but
equal and so the displacement is ZERO. If motion is
involved, it will be constant.
Static equilibrium: where there are NO unbalanced forces
acting on a body, the vector sum of all forces acting on the
body is zero—called the equilibrant force. So if each force is
equal to the other then, the body is either at rest or moving
at a constant speed in a straight line.
Special Case:
If you are ONLY solving for the
equilibrant force, you can use the
Pythagorean Theorem to calculate
the magnitude of the resultant.
**Use only, if 2 sides are known
and direction is NOT needed!
PYTHAGOREAM THEOREM
2
A
+
2
B
=
2
C
C (hypotenuse)
side A
side B
For example:
32 + 42 = C2
?
3
9 + 16 = C2
4
25 = C2
C = √25
C=5
Y
V
X
Vector V has components X & Y
DUE TODAY:
• Vector Fill-in Notes (KEEP)
• Practice Problems & In the Park
“The person lives twice who lives the first life
well.”
Robert Herrick
DUE NEXT CLASS:
• Study for Vector Quiz
• Bring Calculator & Protractor!