Physics Unit 3 FORCES 6-10

Unit 3 Lesson 6

Objectives: Word Problems with VECTORS Do Now  Page 142 Problem 85 Homework  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 Unit 3 Lesson 6

Adding Vectors by Components 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. Unit 3 Lesson 6 SLIDE 2

Adding Vectors by Components If the components are NOT perpendicular, they can be found using trigonometric functions. Vx = V Cosθ Vy = V Sin θ 1) __________ _________ 2)___________ _________ 3)___________ _________ + Total Vx Total Vy Unit 3 Lesson 6 Slide 3 Θ = TAN -1 { V y / V x }

HOMEWORK Lesson 6 3 Vector Problem Graphically Analytically Find the resultant vector (Magnitude and Direction of the THREE FORCE vectors acting on the Object at the origin Unit 3 Lesson 6 Slide 4

Solving the components  X Components Vx = V Cosθ  Ax = 44.0 * COS (28.0) =  Bx = 26.5 *COS (124) =  Cx = 31.0 * COS (270.0) = 0.00  X total =  Y Components Vy = V SINθ  Ay = 44.0 * SIN(28.0) =  By = 26.5 *SIN(124) =  Cy = 31.0 * SIN(270) =  Y total = V = √{[24.031] 2 + [11.63] 2 } V = √{[ ]} = m/s = 26.7 m/s HOMEWORK Lesson 6 3 Vector Problem Graphically Analytically Θ = Tan -1 {11.63/24.031} Θ = Tan -1 { } Θ = degrees Θ = 25.8 degrees Unit 3 Lesson 6 Slide 5

Adding Vectors by Components If the components are NOT perpendicular, they can be found using trigonometric functions. Vx = V Cosθ Vy = V Sin θ 1)____________ _________ 2)___________ _________ 3)___________ _________ + Total V x _________ Total V Y _________ Unit 3 Lesson 6 Slide 7 MAKE UP BLANK Θ = TAN -1 { D 2 / D 1 } Vector 1  ° Vector 2  ° Vector 1  ° Θ =__________ V =__________

Objectives: Word Problems with VECTORS 5.3 Do Now QUIZ Page 125 Practice Prob #6 Page 125 Section Rev #14 Homework  Pg 141 – 142 Problems: 80 – 89 all IN CLASS: Pg 141 – 142 Problems: 80 – 89 all astr.gsu.edu/hbase/vect.html#vec1 Unit 3 Lesson 6a

in work 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?  In Class:  ACTIVE READ Section 5.2  Page 128 Practice Problems #’s 17 – 21 ALL Unit 3 Lesson 7 F net = F applied – F friction ma net = ma applied – μmg Cosθ  Homework:  Page 128 Practice Problems #’s 17 – 21 ALL  Page 130 Practice Problems #’s 22 – 32 EVEN

Example Unit 3 Lesson 7

Friction Kinetic and Static  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  IN CLASS FRICTION  LAB  UNIT 3 LAB I Static and Kinetic Friction with blocks Unit 3 Lesson 8 F net = F applied – F friction (m)a net = (m)a applied – μ(m)g Cosθ

Friction Kinetic and Static  IN CLASS :  Present Your Lab write up  Calculate the coefficient of Static and Kinetic friction Between a wooden block and a table.  Does Weight effect the coefficient?  (Vector Review)  Page 142 #’s 85, 87, 88  (Friction Review)  Page 142 #’s 90, 91, {92, 93, 94}  Homework :  (Vector Review)  Page 142 #’s 85, 87, 88  (Friction Review)  Page 142 #’s 90, 91, {92, 93, 94} Unit 3 Lesson 9

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 Homework: Pg 141 – 142 Problems: 92, 93, 94  Review:  F net = F applied – F friction  ma net = ma applied – μmg Cosθ  Review BIG FIVE Unit 3 Lesson 10