SlideShare a Scribd company logo
Torque
Chapter 9 – Rotational
Dynamics
What is Torque?
 Torque is a rotational force around a fixed
axis or point.
Torque
 Torque is represented using the Greek letter
tau as follows:
τ = Fd sinθ
-Where
F = Force (Newtons)
d = lever arm length
θ = angle that force makes with the
axis of the lever arm
Note: Torque is a vector quantity.
Factors that affect Torque
 Distance: The distance from the point of rotation affects
torque in such a manner that the further you are from the
axis of rotation, the easier it is to rotate around that point.
F1
F2
d2
d1
Note: The distance d is also known as the lever arm.
Factors that affect Torque
 Angle: Torque also depends on the angle at which the
force makes with the lever arm. Torque is maximum
when the force makes a 90° angle with the lever arm.
d
F
θ
θ
Factors that affect Torque
 Force: Torque is directly proportional to the force
applied to the lever arm. As the force increases, so
does the torque.
F1
d
F2
d
F2 > F1
τ2 > τ1
Torque & Seesaws
 Equilibrium: Equilibrium exits when the seesaw is
balanced such that it will not tend to rotate around
the fulcrum.
– At Equilibrium:
 There is no net torque
 There is no net force.
Fulcrum
Conditions for Equilibrium
1. The sum of the forces must equal zero.
– ΣF = F1 + F2 – FF = 0
– ΣF = m1g + m2g – FF = 0
1. The sum of the torques must equal zero.
– Στ = F1d1 + F2d2 = 0
Translational Equilibrium
 The sum of the forces must equal zero.
– ΣF = F1 + F2 – FF = 0
– ΣF = m1g + m2g – FF = 0
F1 F2
FF
Rotational Equilibrium
 The sum of the torques must equal zero.
– Στ = F1d1 + F2d2 = 0
– Note that one torque will provide a rotational force in
the counterclockwise direction (F1) while the other
force will provide a rotational force in the clockwise
direction (F2)
F1 F2
d1 d2
Center of Mass
 If the fulcrum (pivot point) does not occur at
the center of the object, then the center of
mass must be factored into the problem.
 For uniform geometric shapes, the center of
mass can be conveniently chosen at the
center of the object.
Center of Mass
When the Fulcrum is not in the Center
 Στ = F1d1 + F2d2 + FB1dB1 + FB2dB2 = 0
F1
F2
Center of mass of
board relative to the
fulcrum.
FB1
FB2
d1
dB1 dB2
d2
Solving Problems involving Torque
1. Select the object to which the equations for equilibrium are to
be applied.
2. Draw a free-body diagram that shows all of the external
forces acting on the object.
3. Choose a convenient set of x, y axes and resolve all forces
into components that lie along these axes.
4. Apply the equations that specify the balance of forces at
equilibrium. (Set the net force in the x and y directions equal
to zero.)
5. Select a convenient axis of rotation. Set the sum of the
torques about this axis equal to zero.
6. Solve the equations for the desired unknown quantities.
A woman whose weight is 530 N is
poised at the right end of a diving board
with length 3.90 m. The board has
negligible weight and is supported by
a fulcrum 1.40 m away from the left
end.
Find the forces that the bolt and the
fulcrum exert on the board.
Example 1: A Diving
Board
022 =−=∑ WWF τ
( )( ) N1480
m1.40
m90.3N530
2 ==F
2
2

WW
F =
Example 1: A Diving
Board
021 =−+−=∑ WFFFy
0N530N14801 =−+− F
N9501 =F
Example 1: A Diving
Board
Torque Applied to Mobiles
 The mobile can be looked at as a balance of
forces in motion.
 The forces of nature – wind and gravity –
play a significant role in understanding how
mobiles function.
Torque and Mobiles
FM
FE
FS
Στ = 0

More Related Content

What's hot

Centripetal Force
Centripetal ForceCentripetal Force
Centripetal Force
walt sautter
 
Center of mass ppt.
Center of mass ppt.Center of mass ppt.
Center of mass ppt.
ZwebaButt
 
CIRCULAR MOTION
CIRCULAR MOTIONCIRCULAR MOTION
CIRCULAR MOTION
Nurul Fadhilah
 
Relative motion in 1D & 2D
Relative motion in 1D & 2DRelative motion in 1D & 2D
Relative motion in 1D & 2D
KhanSaif2
 
IGCSE PHYSICS: Equilibrium and Centre of Mass
IGCSE PHYSICS: Equilibrium and Centre of MassIGCSE PHYSICS: Equilibrium and Centre of Mass
IGCSE PHYSICS: Equilibrium and Centre of Mass
Rozzie Jhana CamQue
 
IGCSE Pysics Momentum
IGCSE Pysics MomentumIGCSE Pysics Momentum
IGCSE Pysics Momentum
Jen Soriano
 
ROTATIONAL KINEMATICS
ROTATIONAL KINEMATICSROTATIONAL KINEMATICS
ROTATIONAL KINEMATICS
GODFREY MDUDUZI MABENA
 
Turning Effect of Forces
Turning Effect of ForcesTurning Effect of Forces
Turning Effect of Forcesmeenng
 
Turning Effect of Forces
Turning Effect of ForcesTurning Effect of Forces
Turning Effect of Forces
Shafie Sofian
 
Center Of Mass
Center Of MassCenter Of Mass
Center Of Mass
GillianWinters
 
Velocity and acceleration
Velocity and accelerationVelocity and acceleration
Velocity and accelerationamandayoung313
 
Center of gravity
Center of gravityCenter of gravity
Center of gravity
Alladin Polintan
 
Circular motion
Circular motionCircular motion
Circular motion
Mukesh Tekwani
 
Momentum
MomentumMomentum
Center of mass
Center of massCenter of mass
Center of mass
Usman Sajid
 
Weight and MASS.ppt
Weight and MASS.pptWeight and MASS.ppt
Weight and MASS.pptmrmeredith
 
Kinematics
KinematicsKinematics
Kinematics
Shafie Sofian
 
Simple harmonic motion and elasticity
Simple harmonic motion and elasticitySimple harmonic motion and elasticity
Simple harmonic motion and elasticity
Menelisi Mthethwa
 

What's hot (20)

Centripetal Force
Centripetal ForceCentripetal Force
Centripetal Force
 
Momentum
 Momentum Momentum
Momentum
 
Free fall
Free fallFree fall
Free fall
 
Center of mass ppt.
Center of mass ppt.Center of mass ppt.
Center of mass ppt.
 
CIRCULAR MOTION
CIRCULAR MOTIONCIRCULAR MOTION
CIRCULAR MOTION
 
Relative motion in 1D & 2D
Relative motion in 1D & 2DRelative motion in 1D & 2D
Relative motion in 1D & 2D
 
IGCSE PHYSICS: Equilibrium and Centre of Mass
IGCSE PHYSICS: Equilibrium and Centre of MassIGCSE PHYSICS: Equilibrium and Centre of Mass
IGCSE PHYSICS: Equilibrium and Centre of Mass
 
IGCSE Pysics Momentum
IGCSE Pysics MomentumIGCSE Pysics Momentum
IGCSE Pysics Momentum
 
ROTATIONAL KINEMATICS
ROTATIONAL KINEMATICSROTATIONAL KINEMATICS
ROTATIONAL KINEMATICS
 
Turning Effect of Forces
Turning Effect of ForcesTurning Effect of Forces
Turning Effect of Forces
 
Turning Effect of Forces
Turning Effect of ForcesTurning Effect of Forces
Turning Effect of Forces
 
Center Of Mass
Center Of MassCenter Of Mass
Center Of Mass
 
Velocity and acceleration
Velocity and accelerationVelocity and acceleration
Velocity and acceleration
 
Center of gravity
Center of gravityCenter of gravity
Center of gravity
 
Circular motion
Circular motionCircular motion
Circular motion
 
Momentum
MomentumMomentum
Momentum
 
Center of mass
Center of massCenter of mass
Center of mass
 
Weight and MASS.ppt
Weight and MASS.pptWeight and MASS.ppt
Weight and MASS.ppt
 
Kinematics
KinematicsKinematics
Kinematics
 
Simple harmonic motion and elasticity
Simple harmonic motion and elasticitySimple harmonic motion and elasticity
Simple harmonic motion and elasticity
 

Similar to Torque

Engineering Mechanics made simple
Engineering Mechanics made simpleEngineering Mechanics made simple
Engineering Mechanics made simpleProf. S.Rajendiran
 
Chapter 9
Chapter 9Chapter 9
Chapter 9
Younes Sina
 
Torque,stability and equilibrium
Torque,stability and equilibriumTorque,stability and equilibrium
Torque,stability and equilibrium
Elaine Espiel
 
Torque,stability and equilibrium
Torque,stability and equilibriumTorque,stability and equilibrium
Torque,stability and equilibrium
Elaine Espiel
 
Physics 161Static Equilibrium and Rotational Balance Intro.docx
Physics 161Static Equilibrium and Rotational Balance Intro.docxPhysics 161Static Equilibrium and Rotational Balance Intro.docx
Physics 161Static Equilibrium and Rotational Balance Intro.docx
randymartin91030
 
Chapter 2 basic structure concepts
Chapter 2  basic structure conceptsChapter 2  basic structure concepts
Chapter 2 basic structure concepts
Simon Foo
 
1. motion in a circle by a tobve
1.   motion in a circle by a tobve1.   motion in a circle by a tobve
1. motion in a circle by a tobve
Allen Tobve
 
Lecture 4 static_equilibrium
Lecture 4 static_equilibriumLecture 4 static_equilibrium
Lecture 4 static_equilibrium
Khairul Azhar
 
6161103 4.1 moment of a force – scalar formation
6161103 4.1 moment of a force – scalar formation6161103 4.1 moment of a force – scalar formation
6161103 4.1 moment of a force – scalar formationetcenterrbru
 
static friction
static frictionstatic friction
static friction
MARKCHRISTIANTENORIO1
 
Slope stability
Slope stabilitySlope stability
Slope stabilityyoohannis
 

Similar to Torque (20)

Engineering Mechanics made simple
Engineering Mechanics made simpleEngineering Mechanics made simple
Engineering Mechanics made simple
 
Chapter 9
Chapter 9Chapter 9
Chapter 9
 
Torque,stability and equilibrium
Torque,stability and equilibriumTorque,stability and equilibrium
Torque,stability and equilibrium
 
Torque,stability and equilibrium
Torque,stability and equilibriumTorque,stability and equilibrium
Torque,stability and equilibrium
 
Torque
TorqueTorque
Torque
 
Ch9
Ch9Ch9
Ch9
 
Physics 161Static Equilibrium and Rotational Balance Intro.docx
Physics 161Static Equilibrium and Rotational Balance Intro.docxPhysics 161Static Equilibrium and Rotational Balance Intro.docx
Physics 161Static Equilibrium and Rotational Balance Intro.docx
 
Mechanics 3
Mechanics 3Mechanics 3
Mechanics 3
 
Chapter 2 basic structure concepts
Chapter 2  basic structure conceptsChapter 2  basic structure concepts
Chapter 2 basic structure concepts
 
project statics
project staticsproject statics
project statics
 
1. motion in a circle by a tobve
1.   motion in a circle by a tobve1.   motion in a circle by a tobve
1. motion in a circle by a tobve
 
Lecture 4 static_equilibrium
Lecture 4 static_equilibriumLecture 4 static_equilibrium
Lecture 4 static_equilibrium
 
6161103 4.1 moment of a force – scalar formation
6161103 4.1 moment of a force – scalar formation6161103 4.1 moment of a force – scalar formation
6161103 4.1 moment of a force – scalar formation
 
Circular
CircularCircular
Circular
 
static friction
static frictionstatic friction
static friction
 
Lecture02
Lecture02Lecture02
Lecture02
 
Lecture02
Lecture02Lecture02
Lecture02
 
Slope stability
Slope stabilitySlope stability
Slope stability
 
Friction
FrictionFriction
Friction
 
Mekanika teknik
Mekanika teknikMekanika teknik
Mekanika teknik
 

Recently uploaded

Cambridge International AS A Level Biology Coursebook - EBook (MaryFosbery J...
Cambridge International AS  A Level Biology Coursebook - EBook (MaryFosbery J...Cambridge International AS  A Level Biology Coursebook - EBook (MaryFosbery J...
Cambridge International AS A Level Biology Coursebook - EBook (MaryFosbery J...
AzmatAli747758
 
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
EugeneSaldivar
 
1.4 modern child centered education - mahatma gandhi-2.pptx
1.4 modern child centered education - mahatma gandhi-2.pptx1.4 modern child centered education - mahatma gandhi-2.pptx
1.4 modern child centered education - mahatma gandhi-2.pptx
JosvitaDsouza2
 
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
Nguyen Thanh Tu Collection
 
Unit 2- Research Aptitude (UGC NET Paper I).pdf
Unit 2- Research Aptitude (UGC NET Paper I).pdfUnit 2- Research Aptitude (UGC NET Paper I).pdf
Unit 2- Research Aptitude (UGC NET Paper I).pdf
Thiyagu K
 
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
siemaillard
 
Sectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdfSectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdf
Vivekanand Anglo Vedic Academy
 
Instructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptxInstructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptx
Jheel Barad
 
2024.06.01 Introducing a competency framework for languag learning materials ...
2024.06.01 Introducing a competency framework for languag learning materials ...2024.06.01 Introducing a competency framework for languag learning materials ...
2024.06.01 Introducing a competency framework for languag learning materials ...
Sandy Millin
 
The geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideasThe geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideas
GeoBlogs
 
Ethnobotany and Ethnopharmacology ......
Ethnobotany and Ethnopharmacology ......Ethnobotany and Ethnopharmacology ......
Ethnobotany and Ethnopharmacology ......
Ashokrao Mane college of Pharmacy Peth-Vadgaon
 
Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345
beazzy04
 
The Roman Empire A Historical Colossus.pdf
The Roman Empire A Historical Colossus.pdfThe Roman Empire A Historical Colossus.pdf
The Roman Empire A Historical Colossus.pdf
kaushalkr1407
 
The Challenger.pdf DNHS Official Publication
The Challenger.pdf DNHS Official PublicationThe Challenger.pdf DNHS Official Publication
The Challenger.pdf DNHS Official Publication
Delapenabediema
 
Chapter 3 - Islamic Banking Products and Services.pptx
Chapter 3 - Islamic Banking Products and Services.pptxChapter 3 - Islamic Banking Products and Services.pptx
Chapter 3 - Islamic Banking Products and Services.pptx
Mohd Adib Abd Muin, Senior Lecturer at Universiti Utara Malaysia
 
Fish and Chips - have they had their chips
Fish and Chips - have they had their chipsFish and Chips - have they had their chips
Fish and Chips - have they had their chips
GeoBlogs
 
Synthetic Fiber Construction in lab .pptx
Synthetic Fiber Construction in lab .pptxSynthetic Fiber Construction in lab .pptx
Synthetic Fiber Construction in lab .pptx
Pavel ( NSTU)
 
How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...
Jisc
 
Overview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with MechanismOverview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with Mechanism
DeeptiGupta154
 
special B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdfspecial B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdf
Special education needs
 

Recently uploaded (20)

Cambridge International AS A Level Biology Coursebook - EBook (MaryFosbery J...
Cambridge International AS  A Level Biology Coursebook - EBook (MaryFosbery J...Cambridge International AS  A Level Biology Coursebook - EBook (MaryFosbery J...
Cambridge International AS A Level Biology Coursebook - EBook (MaryFosbery J...
 
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...TESDA TM1 REVIEWER  FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
TESDA TM1 REVIEWER FOR NATIONAL ASSESSMENT WRITTEN AND ORAL QUESTIONS WITH A...
 
1.4 modern child centered education - mahatma gandhi-2.pptx
1.4 modern child centered education - mahatma gandhi-2.pptx1.4 modern child centered education - mahatma gandhi-2.pptx
1.4 modern child centered education - mahatma gandhi-2.pptx
 
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
GIÁO ÁN DẠY THÊM (KẾ HOẠCH BÀI BUỔI 2) - TIẾNG ANH 8 GLOBAL SUCCESS (2 CỘT) N...
 
Unit 2- Research Aptitude (UGC NET Paper I).pdf
Unit 2- Research Aptitude (UGC NET Paper I).pdfUnit 2- Research Aptitude (UGC NET Paper I).pdf
Unit 2- Research Aptitude (UGC NET Paper I).pdf
 
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
 
Sectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdfSectors of the Indian Economy - Class 10 Study Notes pdf
Sectors of the Indian Economy - Class 10 Study Notes pdf
 
Instructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptxInstructions for Submissions thorugh G- Classroom.pptx
Instructions for Submissions thorugh G- Classroom.pptx
 
2024.06.01 Introducing a competency framework for languag learning materials ...
2024.06.01 Introducing a competency framework for languag learning materials ...2024.06.01 Introducing a competency framework for languag learning materials ...
2024.06.01 Introducing a competency framework for languag learning materials ...
 
The geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideasThe geography of Taylor Swift - some ideas
The geography of Taylor Swift - some ideas
 
Ethnobotany and Ethnopharmacology ......
Ethnobotany and Ethnopharmacology ......Ethnobotany and Ethnopharmacology ......
Ethnobotany and Ethnopharmacology ......
 
Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345Sha'Carri Richardson Presentation 202345
Sha'Carri Richardson Presentation 202345
 
The Roman Empire A Historical Colossus.pdf
The Roman Empire A Historical Colossus.pdfThe Roman Empire A Historical Colossus.pdf
The Roman Empire A Historical Colossus.pdf
 
The Challenger.pdf DNHS Official Publication
The Challenger.pdf DNHS Official PublicationThe Challenger.pdf DNHS Official Publication
The Challenger.pdf DNHS Official Publication
 
Chapter 3 - Islamic Banking Products and Services.pptx
Chapter 3 - Islamic Banking Products and Services.pptxChapter 3 - Islamic Banking Products and Services.pptx
Chapter 3 - Islamic Banking Products and Services.pptx
 
Fish and Chips - have they had their chips
Fish and Chips - have they had their chipsFish and Chips - have they had their chips
Fish and Chips - have they had their chips
 
Synthetic Fiber Construction in lab .pptx
Synthetic Fiber Construction in lab .pptxSynthetic Fiber Construction in lab .pptx
Synthetic Fiber Construction in lab .pptx
 
How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...How libraries can support authors with open access requirements for UKRI fund...
How libraries can support authors with open access requirements for UKRI fund...
 
Overview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with MechanismOverview on Edible Vaccine: Pros & Cons with Mechanism
Overview on Edible Vaccine: Pros & Cons with Mechanism
 
special B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdfspecial B.ed 2nd year old paper_20240531.pdf
special B.ed 2nd year old paper_20240531.pdf
 

Torque

  • 1. Torque Chapter 9 – Rotational Dynamics
  • 2. What is Torque?  Torque is a rotational force around a fixed axis or point.
  • 3. Torque  Torque is represented using the Greek letter tau as follows: τ = Fd sinθ -Where F = Force (Newtons) d = lever arm length θ = angle that force makes with the axis of the lever arm Note: Torque is a vector quantity.
  • 4. Factors that affect Torque  Distance: The distance from the point of rotation affects torque in such a manner that the further you are from the axis of rotation, the easier it is to rotate around that point. F1 F2 d2 d1 Note: The distance d is also known as the lever arm.
  • 5. Factors that affect Torque  Angle: Torque also depends on the angle at which the force makes with the lever arm. Torque is maximum when the force makes a 90° angle with the lever arm. d F θ θ
  • 6. Factors that affect Torque  Force: Torque is directly proportional to the force applied to the lever arm. As the force increases, so does the torque. F1 d F2 d F2 > F1 τ2 > τ1
  • 7. Torque & Seesaws  Equilibrium: Equilibrium exits when the seesaw is balanced such that it will not tend to rotate around the fulcrum. – At Equilibrium:  There is no net torque  There is no net force. Fulcrum
  • 8. Conditions for Equilibrium 1. The sum of the forces must equal zero. – ΣF = F1 + F2 – FF = 0 – ΣF = m1g + m2g – FF = 0 1. The sum of the torques must equal zero. – Στ = F1d1 + F2d2 = 0
  • 9. Translational Equilibrium  The sum of the forces must equal zero. – ΣF = F1 + F2 – FF = 0 – ΣF = m1g + m2g – FF = 0 F1 F2 FF
  • 10. Rotational Equilibrium  The sum of the torques must equal zero. – Στ = F1d1 + F2d2 = 0 – Note that one torque will provide a rotational force in the counterclockwise direction (F1) while the other force will provide a rotational force in the clockwise direction (F2) F1 F2 d1 d2
  • 11. Center of Mass  If the fulcrum (pivot point) does not occur at the center of the object, then the center of mass must be factored into the problem.  For uniform geometric shapes, the center of mass can be conveniently chosen at the center of the object. Center of Mass
  • 12. When the Fulcrum is not in the Center  Στ = F1d1 + F2d2 + FB1dB1 + FB2dB2 = 0 F1 F2 Center of mass of board relative to the fulcrum. FB1 FB2 d1 dB1 dB2 d2
  • 13. Solving Problems involving Torque 1. Select the object to which the equations for equilibrium are to be applied. 2. Draw a free-body diagram that shows all of the external forces acting on the object. 3. Choose a convenient set of x, y axes and resolve all forces into components that lie along these axes. 4. Apply the equations that specify the balance of forces at equilibrium. (Set the net force in the x and y directions equal to zero.) 5. Select a convenient axis of rotation. Set the sum of the torques about this axis equal to zero. 6. Solve the equations for the desired unknown quantities.
  • 14. A woman whose weight is 530 N is poised at the right end of a diving board with length 3.90 m. The board has negligible weight and is supported by a fulcrum 1.40 m away from the left end. Find the forces that the bolt and the fulcrum exert on the board. Example 1: A Diving Board
  • 15. 022 =−=∑ WWF τ ( )( ) N1480 m1.40 m90.3N530 2 ==F 2 2  WW F = Example 1: A Diving Board
  • 16. 021 =−+−=∑ WFFFy 0N530N14801 =−+− F N9501 =F Example 1: A Diving Board
  • 17. Torque Applied to Mobiles  The mobile can be looked at as a balance of forces in motion.  The forces of nature – wind and gravity – play a significant role in understanding how mobiles function.