Physics Unit 3
FORCES
6-10
Unit 3 Lesson 6
Unit 3 Lesson 6
Objectives:
Word Problems with
VECTORS
Do Now
 Page
Homework

142 Problem 85
3 Vector Problem

Slide 1 (make “blank” copies)

Solve for Resultant and direction

Page 121 #4
Page 125 Practice Problems 5 – 10
Page 125 Section Review 11 – 15
Vectors Components on the next 4
slides



IN CLASS:
Page 121 #4
Page 125 Practice Problems 5 – 10
Page 125 Section Review 11 – 15
Vectors Components on the next 4 slides
Adding Vectors by
Components
Unit 3 Lesson 6
SLIDE 2
Any vector can be expressed as the sum of two
other vectors, which are called its components.
Usually the other vectors are chosen so that they
are perpendicular to each other.
Adding Vectors
by Components
Unit 3 Lesson 6
Slide 3
If the components are NOT
perpendicular,
they can be found using
trigonometric functions.
Vx = V Cosθ
1) __________
2) ___________
3) ___________
+
Total Vx
Vy = V Sin θ
_________
_________
_________
Total Vy
Θ = TAN-1 { Vy / Vx}
HOMEWORK Lesson 6
3 Vector Problem
Graphically
Analytically
Unit 3 Lesson 6
Slide 4
Find the resultant vector
(Magnitude and Direction
of the THREE FORCE
vectors acting on the
Object at the origin
HOMEWORK Lesson 6
3 Vector Problem
Graphically Analytically
Unit 3 Lesson 6
Slide 5
Solving the components





X Components Vx = V Cosθ
Ax = 44.0 * COS (28.0) = 38.85
Bx = 26.5 *COS (124) = - 14.82
Cx = 31.0 * COS (270.0) = 0.00
X total = 24.031

Y Components Vy = V SINθ
Ay = 44.0 * SIN(28.0) = 20.66
By = 26.5 *SIN(124) = 21.97
Cy = 31.0 * SIN(270) = - 31.0

Y total = 11.63



V = √{[24.031]2 + [11.63]2}
Θ = Tan-1 {11.63/24.031}
V = √{[24.031]2 + [11.63]2}
V = √{[712.748]} = 26.6973 m/s Θ = Tan-1 {0.483958}
Θ = 25.8225 degrees
= 26.7 m/s
Θ = 25.8 degrees
Adding Vectors
by Components
Vector 1  24.0 m/s @ 200.0°
Vector 2 12.0 m/s @ 45.0°
Vector 1  48.0 m/s @ 330.0°
Unit 3 Lesson 6
Slide 7 MAKE UP BLANK
If the components are NOT
perpendicular,
they can be found using
trigonometric functions.
Vx = V Cosθ
1) ____________
2) ___________
3) ___________
+
Total Vx _________
Θ = TAN-1 { D2 / D1}
V =__________
Vy = V Sin θ
_________
_________
_________
Total VY _________
Θ =__________
Unit 3 Lesson 6a
Objectives:
Word Problems with VECTORS 5.3
Homework
 Pg 141 – 142 Problems:
80 – 89 all
Do Now
QUIZ
Page 125 Practice Prob #6
Page 125 Section Rev #14
IN CLASS:
Pg 141 – 142 Problems: 80 – 89 all
http://hyperphysics.phyastr.gsu.edu/hbase/vect.html#vec1
Unit 3 Lesson 7
FRICTION in work
Static and Kinetic
Do Now: If Andrew (applied) pushes
Mr. Romac with a force of 25.0 N.
The class measures Mr. Romac
sliding across the linoleum floor
with a net force of 20.0 N.
What is the frictional force
between Mr. Romac’s shoes and
the linoleum floor?
Fnet = Fapplied – F friction
manet = maapplied – μmg Cosθ



In Class:
ACTIVE READ Section 5.2
Page 128 Practice Problems
#’s 17 – 21 ALL



Homework:
Page 128 Practice
Problems #’s 17 – 21 ALL
Page 130 Practice
Problems #’s 22 – 32 EVEN
Unit 3 Lesson 7
Example
Unit 3 Lesson 8
Friction Kinetic and Static
Fnet = Fapplied – F friction
(m)anet = (m)aapplied – μ(m)g Cosθ
 IN
CLASS FRICTION
 LAB
 UNIT 3 LAB I Static
and Kinetic Friction
with blocks






Homework: Complete the
Lab write up
Calculate the coefficient
of Static and Kinetic
friction Between a
wooden block and a
table.
Does Weight effect the
coefficient?
Use the handout
UNIT 3 LAB I Static and Kinetic Friction
with blocks
and Page 136 Physics LAB
Unit 3 Lesson 9
Friction Kinetic and Static
 IN



Present Your Lab write up
Calculate the coefficient of
Static and Kinetic friction
Between a wooden block and  Homework:
a table.
 (Vector Review)
Does Weight effect the
 Page 142 #’s 85, 87, 88
coefficient?
 (Friction Review)


(Vector Review)
Page 142 #’s 85, 87, 88


CLASS:
(Friction Review)
Page 142 #’s 90, 91, {92, 93 , 94}

Page 142 #’s 90, 91, {92, 93 , 94}
Finalize Friction
Do Now: QUICK LAB
A ball rolls to a stop 2.55
meters of roll after having
an initial velocity of 3.5
m/s.
What is the coefficient of
friction between a ball and
the carpet .
 In
Class:
 Quick Lab Write up
Unit 3 Lesson 10
Homework:
Pg 141 – 142
Problems:
92, 93, 94
 Review:
 Fnet = Fapplied – F friction
 manet = maapplied – μmg Cosθ
 Review
BIG FIVE