Instructor’s Manual9501237cd28d19b2179e-2b95e1c35361852316f29268b55e4faf.r43.cf1.rackcdn.com/...Instructor’s Manual. ... except for brief quotations embodied in critical articles

Barney F. LeVeau, PT, PhD ProFessor, DeParTmenT oF PhysicaL TheraPy

coLLege oF heaLTh sciences aLaBama sTaTe uniVersiTy

monTgomery, aL

Instructor’s Manual

Copyright © 2011 by SLACK Incorporated

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The procedures and practices described in this book should be implemented in a manner consistent with the professional standards set for the circumstances that apply in each specific situation. Every effort has been made to confirm the accuracy of the information presented and to correctly relate generally accepted practices. The authors, editor, and publisher cannot accept responsibility for errors or exclusions or for the outcome of the material presented herein. There is no expressed or implied warranty of this book or information imparted by it. Care has been taken to ensure that drug selection and dosages are in accordance with currently accepted/recommended practice. Due to continuing research, changes in government policy and regulations, and vari-ous effects of drug reactions and interactions, it is recommended that the reader carefully review all materials and literature provided for each drug, especially those that are new or not frequently used. Any review or men-tion of specific companies or products is not intended as an endorsement by the author or publisher.

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Copyright © 2011 SLACK Incorporated from LeVeau BF. Biomechanics of Human Motion: Basics and Beyond for the Health Professions. Thorofare, NJ.

ContentsSection 1: Practice Problems ...............................................................................................................4 Answers ..........................................................................................................................12

Section 2: Quizzes ................................................................................................................................13 Force ...............................................................................................................................13 Strength of Materials ...................................................................................................13 Composition and Resolution of Forces ....................................................................15 Equilibrium ...................................................................................................................15 Friction ...........................................................................................................................19 Dynamics .......................................................................................................................20 Application ....................................................................................................................21 Answers ..........................................................................................................................22

Section 3: Examination Questions ..................................................................................................26 Multiple Choice.............................................................................................................26 Chapter 1 ................................................................................................................26 Chapter 2 ................................................................................................................27 Chapter 3 ................................................................................................................28 Chapter 4 ................................................................................................................31 Chapter 5 ................................................................................................................32 Chapter 6 ................................................................................................................32 Chapter 7 ................................................................................................................34 Short Answer ................................................................................................................35 Problems ........................................................................................................................36 Answers ..........................................................................................................................46

Practice Problems

section 1

1. Compare the resultants of the 3 sets of forces. Which resultant has the greatest magnitude? Why?

A = B = C =

2. Compare the moments of the following situations. Which has the greatest moment? Why?

Moment A = Moment B = Moment C =


Practice Problems �

3. Solve for F.

4. Solve for A and B.


F =

A = B =

� Practice Problems

5. Solve for PFJF.

a. What happens to the PFJF if the angles change to 85 degrees? 35 degrees? At 85 degrees, PFJF _________ ; At 35 degrees, PFJF __________

6. Solve for F and W.

7. Solve for J.


F = W =

PFJF =

J =


8. Solve for A, B, and F.



A = B = F =

A = B = F =

� Practice Problems

10. Solve for F.


12. Solve for F and J.


F = J =

F =

A = B = F =


13. SolveforM,Jandλ.

14. SolveforM,J,andλ.


M = J = λ=

λ

M = J = λ=

λ

10 Practice Problems

15. SolveforF,J,andλ.

16. Solvefortheforce,F,neededtomovetheboxifμ=0.2.


F = J = λ=

F =

Practice Problems 11

17. Find the perpendicular force components of W (Wx and Wy) where Wy represents the normal force.

a. Whatisthedirectionandmagnitudeofthefrictionalforceifμ=0.2? ff = b. Will the box slide or remain in place? c. How much force is needed to slide the box up the ramp?

18. Calculate the following from elbow flexion figure. t = 0.2 sec


Wx = Wy =

Θinradians= sH = vH = ωindegrees/sec= ωinradians/sec=

0

12 Practice Problems

Answers 1. A = 33.64 lb; B = 20 lb; C = 10.35 lb In A, the forces are acting more together than in C, where they are acting against each

other. 2. Moment A = 100 in/lb; Moment B = 141.4 in/lb; Moment C = 200 in/lb The lever arm is longer in C. 3. F = 28.28 lb 4. A = 70.7 lb; B = 70.7 lb 5. PFJF = 422.6 lb

a. decreases; increases 6. F = 30 lb; W = 20 lb 7. J = 19.32 lb 8. A = 10 lb; B = 20 lb; F = 10 lb 9. A = 26 lb; B = 13 lb; F = 13 lb 10. F = 13.83 lb 11. A = 15 lb; B = 30 lb; F = 15 lb 12. F = 10 lb; J = 15 lb 13. M=85.13lb;J=72.66lb;λ=68.2degrees 14. M=193.98lb;J=178.6lb;λ=27degrees 15. F=18.75lb;J=21.25lb;λ=28degrees 16. F = 10 lb 17. Wx = Wsin30º; Wy = Wcos30º Wx = 50 lb down the ramp; Wy = 86.6 lb

a. ff=λN;ff=λWy;ff = 17.32 lb up the ramp b. slide c. F = Wx + ff; F = 67.32 lb

18. Θ=2.09rad;sH = 41.88 in; vH=209.4in/sec;ω=600degrees/sec;ω=10.47rad/sec



Quizzes 13

Quizzes

section 2

Force 1. Define force.

2. List the 4 characteristics of force and draw a figure representing each characteristic.

3. Name 6 of the 8 types of force used in physical therapy and give an example of each.

4. Differentiate scalar and vector.

5. What are 2 definitions of strength?

6. What is pressure?

Strength of Materials 1. The change in length divided by its original length is called ______________.

2. The internal reaction to a load is called _______________.

3. List the 3 principle strains and draw an example of each.

4. When bending a rod, the concave side of the rod is placed under ____________ stress. a. compression b. tension c. torsion d. shearing


5. Loading a material “off center” is _______________ loading. a. axial b. eccentric c. torsion d. shear

6. Spondylolysthesis is an example of _______________ strain. a. compression b. tension c. torsion d. shearing

7. The failure of a material caused by repeated cyclic loading is _______________ .

8. _____________ occurs as material is continuously loaded for a prolonged time.

9. ______________ is the ability to return to its original size and shape with vigor.

10. From the following figure, provide the labels for:

14 Quizzes

X = Y = A = B = E = U = R =


Composition and Resolution of Forces 1. The single force obtained by combining forces is called the ________________ .

2. The process of separating a force into its perpendicular components is called ________ .

3. If the sacral angle increases from 45 degrees to 65 degrees, the compression on the disc: a. increases b. decreases c. remains the same

4. As the angle between 2 forces decreases from 180 degrees, the resultant force: a. increases b. decreases c. remains the same

5. The rotatory component of the weight of the arm _______________ as the arm moves from the anatomical position to 90 degrees of abduction. a. increases b. decreases c. remains the same

6. FindtheforceF,andtheangleΘ.

Equilibrium 1. What are the 2 conditions of equilibrium?

2. Define moment.

3. At which angle of shoulder abduction does the limb weight give the greatest resistance? a. 45 degrees b. 0 degrees c. 90 degrees

Quizzes 1�

F = Θ=


4. The muscle provides the greatest amount of rotatory force when it inserts at: a. 0 degrees b. 30 degrees c. 60 degrees d. 90 degrees

5. Solve the following problem:

6. Solve the following problem:

7. Which lever class has the axis or fulcrum between the resistance and effort? a. first class b. second class c. third class

8. Which lever class has the effort between the resistance and axis or fulcrum? a. first class b. second class c. third class

9. Which lever class has the resistance between the axis or fulcrum and effort? a. first class b. second class c. third class

1� Quizzes

A = B =

H = V =


10. Solve the following problems:

Quizzes 1�

A) L =

C) F =

D) F = A =

B) A = B = F =


11. What is the value of the moment acting around an axis?

12. IsFcausingaclockwiseorcounterclockwisemoment?Θ=30degrees;d=10in;F=10lb.

13. Find A and B in the following figure:

a. Is B causing a clockwise or counterclockwise moment? b. Is the 150 lb force causing a clockwise or counterclockwise movement?

14. Solve for F, then find R.

1� Quizzes

A = B =

F = R =


Friction 1. Upon what 2 factors does the force of friction depend?

2. Give 2 examples of friction in physical therapy practice.

3. Findtheforceneededtostartslidingthebox.μ=0.3


5. What 3 forces are involved as you begin to slide a 100 lb box up a 30 degree ramp? Draw a figure and show these forces.


Quizzes 1�

F =

Wx = Wy =

a. What is the direction and magnitude of the frictionalforceifμ=0.2?

ff = b. Will the box slide or remain in place? c. How much force is needed to slide the box up

the ramp?

F =


Dynamics 1. Differentiate between kinematics and kinetics.

2. What are the 4 characteristics to describe motion?

3. What2 factorsareadded to thestaticΣM=0equationwhen the limbmovesapulleyweight?

4. What 2 factors affect the moment of inertia of an object? What is the equation for I?

5. Calculate the following from the figure. t = 0.25 sec; Θ = 86 degrees/57.3 degrees; s=rΘ;vA = s/0.25 sec

6. Differentiate between centrifugal and centripetal force.

7. What 2 factors are added to the statics equation in order to calculate the muscle force as a client moves a pulley weight?

8. If a cast is added to the foot and ankle, the combined moment of inertia: a. decreases b. increases c. remains the same

9. As an individual changes from walking to running, what happens to the flexion of the knee? a. decreases b. increases c. remains the same

10. Whatadditionalfactormustbeincludedinthemomentsequation(ΣM=0)whenalimbis rotated such as flexing the elbow?

20 Quizzes

Θinradians= s = vA =


11. Calculate the following from the figure. t = 0.2 sec

12. Define linear and angular work.

13. Differentiate potential and kinetic energy.

Application 1. What are 8 criteria of a measurement instrument?

2. On what 4 characteristics does the stability of an object depend?

True or FaLse 3. We measure muscle strength directly.

4. The muscle produces the greatest moment (torque) when its line of application is at 90 degrees to the bone.

5. The limb provides the greatest resistance moment from gravity when it is vertical.

6. The longer the muscle, within its physiological length, the greater force it produces.

7. A concentric muscle contraction produces more measurable force than either eccentric or isometric contractions. a. Briefly explain your answer to question #7.

8. The muscle produces the least moment (torque) when its line of application is at 90 degrees to the bone.

9. The limb provides the greatest resistance moment from gravity when it is horizontal.

10. The shorter the muscle, within its physiological length, the greater force it produces.

Quizzes 21



AnswersForce 1. push or pull 2.

3. gravitational; contact; frictional; muscular; inertial; elastic; buoyant; electromagnetic (eddy currents)

4. Scalar has magnitude, but no direction; vector has magnitude and direction. 5. (1) The ability of a muscle to produce or resist force and (2) the strength of a material is

the ability of the material or object to resist deformation. 6. the total force per area over which the force is applied

sTrengTh oF maTeriaLs 1. strain 2. stress 3. tension, compression, shear

4. a. compression 5. b. eccentric 6. d. shearing 7. mechanical fatigue 8. creep

22 Quizzes


9. resilience 10. X = strain Y = stress A = elastic range B = plastic range E = elastic limit U = ultimate strength R = rupture strength

comPosiTion anD resoLuTion oF Forces 1. resultant 2. resolution 3. b. decreases 4. a. increases 5. a. increases 6. F=11.23lb;Θ=26.57degrees

equLiBrium 1. (1)Thesumoftheforcesactingonanobjectequalszero(ΣF=0)and(2)thesumofthe

torquesactingonanobjectmustequalzero(ΣM=0). 2. Application of force (F) at a distance (d) from an axis; the moment = F x d. 3. c. 90 degrees 4. d. 90 degrees 5. A = 90 lb; B = 30 lb 6. H = 17.32 lb; V = 10 lb 7. a. first class 8. c. third class 9. b. second class 10. A) L = 20 lb B) A = 100 lb; B = 200 lb; F = 100 lb C) F = 173.2 lb D) F = 50 lb; A = 100 lb 11. Moment = 8.66 in/lb 12. clockwise 13. A = 100 lb; B = 50 lb

a. clockwise b. clockwise around B; counterclockwise around A

14. F = 20 lb; R = 40 lb

Quizzes 23


FricTion 1. normal force and coefficient of friction 2. Many answers exist; see pages 6 and 99-101 in the text Biomechanics of Human Motion: Basics

and Beyond for the Health Professions. 3. F = 6 lb 4. F = 4 lb 5. gravity (W), friction (Ff), applied force (f)

6. Wx = Wsin30º; Wy = Wcos30º Wx = 100 lb down the ramp; Wy = 173.2 lb

a. ff=λN;ff=λWy;ff = 34.64 lb up the ramp b. slide c. F = Wx + ff; F = 134.64 lb

Dynamics 1. Kinematics is the study of the characteristics of motion; kinetics is the study of the forces

that affect motion. 2. displacement, velocity, acceleration, time 3. limb angular acceleration + load acceleration 4. Mass and its radius (distance from the axis of motion) 5. Θ=1.5rad;s=30in;vA = 120 in/sec 6. Centrifugal is inertia or force away from the center; centripetal is force toward the center

or axis. 7. Moment of inertia of limb and moment of inertia of the pulley load 8. b. increases 9. b. increases 10. moment of inertia of limb 11. Θ=2.094rad;sH = 31.41 in; vH=157.05in/sec;ω=600degrees/sec;ω=10.47rad/sec

24 Quizzes


12. Linear work involves a force or forces that cause an object to move a given distance or to change its velocity. Angular work involves torque moving an object through an arc.

13. Potential energy is stored energy related to position, PE = mgh. Kinetic energy is energy related to motion, KE = 1 _ 2 mv2.

aPPLicaTion 1. ability to discriminate; quantifiable; reliable; valid; standardized; ease of administration;

economy of time; availability of norms 2. increasing the mass of the object; increasing the area of the base; lowering the center of

mass of the object; keeping the center of mass directly over the center of the base 3. false 4. true 5. false 6. true 7. false

a. Some of the force during concentric is used for acceleration. 8. false 9. true 10. false

Quizzes 2�


2� Examination Questions

Examination Questions

section 3

Multiple ChoicechaPTer 1 1. If the area of the pad on a brace is increased, what happens to the pressure under the

pad? a. increases b. decreases c. remains the same

2. The greater the mass of an object, the ________ force is needed to decelerate the object. a. more b. less c. same

3. Power is defined as: a. force per area (F/A) b. velocity per time (V/t) c. force times distance (Fd) d. work per time (W/t)

4. Pressure is defined as: a. force per area (F/A) b. velocity per time (V/t) c. force times distance (Fd) d. work per time (W/t)


Examination Questions 2�

5. Work is defined as: a. force per area (F/A) b. velocity per time (V/t) c. force times distance (Fd) d. work per time (W/t)

chaPTer 2 1. The change in a material’s dimensions undergoing tension is called:

a. compression b. shear c. stress d. strain e. work

2. The rupture of material undergoing repetitive loading is called: a. action-reaction b. creep c. fatigue d. pressure e. resilience

3. The coordinates of a curve that commonly illustrate the strength of material properties of a material are: a. stress-strain b. load-force c. creep-fatigue d. elastic-plastic e. strength-rupture

4. The characteristic of a material to fail following prolonged loading is: a. creep b. fatigue c. resilience d. ductility

5. The plastic range for a stress-strain curve of a material is: a. its breaking point b. its ultimate strength c. the area in which a loaded material will return to its original length if unloaded d. the area in which a loaded material will not return to its original length if unloaded,

but will remain deformed



6. The property of elasticity: a. is incompatible with biological materials b. responds to rate of loading of the material c. tends to return the material to its original size and shape

7. When bending a rod, the concave side of the rod is placed under ___________ stress. a. compression b. tension c. torsion d. shearing e. cantilever

8. When bending a rod, the convex side of the rod is placed under ___________ stress. a. compression b. tension c. torsion d. shearing e. cantilever

chaPTer 3 1. When 2 or more forces are combined to obtain a single outcome, the process is called:

a. addition of forces b. resolution of forces c. composition of forces d. vectoring of forces

2. When 1 force is partitioned into 2 perpendicular component forces, the process is called: a. subtraction of forces b. resolution of forces c. composition of forces d. division of forces

3. As the angle between 2 concurrent forces increases, the resultant force: a. increases b. decreases c. remains the same d. none of the above



4. Increasing the sacral angle: a. decreases the shearing component on L5S1 b. increases the shearing component on L5S1 c. increases the compression component on L5S1 d. has no affect on the force components e. both a and c

5. As the angle that a muscle inserts decreases from 90 degrees, the muscle force needed to maintain the body part in its original position: a. increases b. decreases c. remains the same

6. Forces that meet at a point are: a. colinear b. concurrent c. parallel d. scalar

7. A muscle that pulls along the shaft of a bone has a ______________ rotatory effect than one that pulls perpendicular to the shaft of a bone. a. greater b. smaller c. similar

8. As the position of the body part (eg, forearm) moves from the horizontal position, its resis-tance moment: a. increases b. decreases c. stays the same

9. The rotatory component of a muscle is the force component that: a. is parallel to the bone b. is perpendicular to the bone c. tends to cause movement of the bone around the joint axis d. tends to cause force into the joint e. both b and c f. both a and d


30 Examination Questions

10. At which angle of shoulder abduction does the limb weight give the greatest resistance? a. 0 degrees b. 45 degrees c. 90 degrees d. 120 degrees

11. The muscle provides the greatest amount of rotatory force when it inserts at: a. 0 degrees b. 30 degrees c. 60 degrees d. 90 degrees

12. As the position of the body part (eg, forearm) moves from the horizontal position, its resis-tance moment: a. increases b. decreases c. stays the same

13. What happens to patellarfemoral joint force during a squat if the knee angle changes from 20 degrees to 80 degrees? a. increases b. decreases c. remains the same

14. If the sacral angle increases from 45 degrees to 60 degrees, the compression on the disc: a. increases b. decreases c. remains the same

15. As the angle between 2 forces decreases from 180 degrees, the resultant force: a. increases b. decreases c. remains the same

16. The rotatory component of the weight of the arm ____________ as the arm moves from the anatomical position to 90 degrees of abduction. a. increases b. decreases c. remains the same


Examination Questions 31

chaPTer 4 1. The Second Condition of Equilibrium is:

a. ∑F = O b. ∑M = O c. Law of Inertia d. Law of Acceleration e. Law of Reaction

2. Which lever class has the axis or fulcrum between the resistance and effort? a. first class b. second class c. third class

3. Which lever class has the effort between the resistance and axis or fulcrum? a. first class b. second class c. third class

4. Which lever class has the resistance between the axis or fulcrum and effort? a. first class b. second class c. third class

5. Which lever class always has a mechanical advantage less than 1? a. first class b. second class c. third class

6. Which lever class always has a mechanical advantage greater than 1? a. first class b. second class c. third class

7. What is the difference between a fixed pulley and a movable pulley? a. A fixed pulley increases the mechanical advantage. b. A movable pulley only changes direction of the force. c. No difference. d. For a movable pulley, less force is needed to move a load.

8. The line of joint reaction is often almost parallel to the muscle force. Why? a. This statement is rarely true. b. The line of muscle force is usually the greatest force of the forces involved to produce

the joint reaction force. c. The line of joint reaction force is always parallel to the line of the muscle force.



chaPTer 5 1. The frictional force between 2 objects depends upon:

a. the normal force between them b. the type of contacting surfaces c. the area of the contacting surfaces d. more than 1 of the above e. none of the above

2. If the coefficient of friction is 0.3 between a 100 lb box and its supporting surface, the horizontal force needed to begin sliding the box is: a. 10 lb b. 20 lb c. 30 lb d. 40 lb

3. If 5 lb is needed to begin sliding a 20 lb box, the coefficient friction between the box and the supporting surface is: a. 0.2 b. 0.25 c. 0.4 d. 0.5

4. What is the greatest angle of a ramp that will allow a wheelchair to ascend the ramp if the coefficient of friction is 0.106? a. 12 degrees b. 10 degrees c. 8 degrees d. 6 degrees e. 4 degrees

5. If the coefficient of friction is 0.2 between the wheelchair wheels and the sidewalk, the wheelchair will be able to proceed up a hill of 15 degrees. a. true b. false

chaPTer 6 1. If a cast is added to the foot and ankle, the combined moment of inertia:

a. decreases b. increases c. remains the same



2. As an individual changes from running to walking, what happens to the flexion of the knee? a. decreases b. increases c. remains the same

3. As an individual changes from walking to running, what happens to the flexion of the knee? a. decreases b. increases c. remains the same

4. The force that causes an object to keep from flying away from the center of motion is: a. inertia b. centrifugal force c. centripetal force d. tangential acceleration

5. Angular work is defined by the equation: a. Fs b. TΘ c. ½Iα d. mas e. Iω

6. When a skater is spinning and the extended upper limb flexes, what happens to her angular velocity? a. decreases b. increases c. remains the same

7. As the upper limb swings through an arc with the elbow extended, the linear velocity of the elbow is ___________ that of the hand. a. greater than b. less than c. equal to

8. If an AFO (ankle-foot-orthosis) is added to the lower limb, the combined moment of inertia of the lower limb and orthosis is _______ the moment of inertia of the lower limb itself. a. greater than b. less than c. equal to



9. Increasing the radius of a limb by extending it away from the midline of the body does what to the angular velocity of a spinning body? a. increases it b. decreases it c. it remains the same

10. As an individual walks faster, the elbow joint: a. increases flexion b. increases extension c. remains the same

11. Which formula may be used to change angular displacement to linear displacement? a. T=Iα b. F = ma c. V = d/t d. s=rΘ

chaPTer 7 1. When sitting in a wheelchair, the center of mass of a patient with bilateral above-knee

amputation compared with a person with both limbs intact is: a. up and forward b. up and backward c. no difference d. down and forward e. down and backward

2. When standing, the center of mass of a patient with a single transfemoral amputation of the right limb compared with a person with both limbs intact is: a. up and to the right b. up and to the left c. no difference d. down and to the right e. down and to the left

3. During quadriceps muscle exercise with the patient in the sitting position, a sandbag attached to the ankle will provide the greatest resistance to the quadriceps muscles when the knee is: a. extended b. flexed c. at 45 degrees d. position makes no difference



4. An object is more stable if: a. its center of mass is high b. its center of mass is near the edge of its base of support c. it has a large base of support d. all of the above increase stability e. none of the above increase stability

5. Of the given positions during the knee bend (squat) exercise, the patellofemoral joint force is probably greatest: a. at full extension b. at 45 degree flexion c. at 90 degree flexion

6. The __________ a given load is in relation to the joint, the greater the moment it will produce. a. closer b. further c. no difference

7. The _________ the muscle, within its physiological length, the greater force it produces. a. shorter b. longer c. no difference

8. A(n) ______________ muscle contraction produces the most measurable force. a. concentric b. eccentric c. isometric

9. A(n) _______________ muscle contraction produces the most actual muscle force. a. concentric b. eccentric c. isometric

Short Answer 1. Draw and label a diagram showing the 4 characteristics of force.

2. List 8 types of force and give an example of each.

3. The change in length divided by its original length is called ___________.



4. The internal reaction to a load is called ____________.

5. The failure of a material caused by repeated cyclic loading is ____________.

6. __________ occurs as material is continuously loaded for a prolonged time.

7. __________ is the ability to return to its original size and shape with vigor.

8. The single force obtained by combining forces is called the _____________.

9. The process of separating a force into its perpendicular components is called ________ .

10. What happens to PFJF if the angles change from 45 degrees to 85 degrees? 35 degrees?

11. What are the 2 conditions of equilibrium?

12. Upon what 2 factors does the force of friction depend?

13. What 3 forces are involved as you begin to slide a 100 lb box up a 30 degree ramp?

14. What 2 factors are added to the statics equation in order to calculate the muscle force as a client moves a pulley weight?

15. What 2 factors affect the moment of inertia of an object?

16. On what 4 characteristics does the stability of an object depend?

17. What are 8 criteria of a measurement instrument?

Problems 1. Solve for H and V. H = V =



2. Solve for F.


4. Solve for PFJF.

F =

A = B =

PFJF =



5. Solve the following problems.

6. Solve for F and A.

A) L = B) A = B = F =

C) F =

F = A =




8. Whatisthevalueofthemomentactingaroundanaxis?Θ=30degrees;d=10in;F=10lb

9. Find A and B in the following figure.

a. Is B causing a clockwise or counterclockwise moment? b. Is the 150 lb force causing a clockwise or counterclockwise movement?

A = B =

A = B =

Moment =



10. During the loading response of gait, a 200 lb man must use how many pounds of hip abductor muscle force (M) to keep his pelvis level? The muscle attaches 2 in from the hip joint and the superincumbent weight of 130 lb is located 5 in from the hip joint. What is the joint reaction force ( J) at the hip?

a. The body weight is tending to cause ____________ moment around the hip joint. a. a clockwise b. a counterclockwise c. no

11. A man is lifting a 200 lb load (F) that is acting counterclockwise on the trunk. The trunk is flexed at a 30 degree angle with the vertical or 60 degrees above the horizontal. What is the magnitude of the moment caused by this load?

M = J =

Moment =




13. Find the abductor muscle force (F) needed to hold the weight (W) and load (L) and the magnitude( J)andangle(Θ)ofthehipjointforceinthefollowingfigure.

14. SolveforM,JandΘ.

A = B =

M = J = Θ=

F = J = Θ=




16. Solve for F.


A = B = F =

F =

A = B = F =

18. Inthefollowingfigure,whatwouldbetheforceoffrictionifμ=0.3?

a. How much force (F) would be needed to overcome the force of friction? F = b. To keep from tipping the box, what is the distance (d) above the floor that you should

apply the force, F? d =




Ff =

F =


a. Whatisthedirectionandmagnitudeofthefrictionalforceifμ=0.2? b. Will the box slide or remain in place? c. How much force is needed to slide the box up the ramp?

21. CalculateΘ,s,andvA from the following the figure. t = 0.25 sec



Wx = Wy =

Θinradians= s = vA =





Θinradians= ωinradians/sec= sA = vA =


AnswersmuLTiPLe choice

Chapter 1 1. b. decreases 2. a. more 3. d. work per time (W/t) 4. a. force per area (F/A) 5. c. force times distance (Fd)

Chapter 2 1. d. strain 2. c. fatigue 3. a. stress-strain 4. a. creep 5. d. the area in which a loaded material will not return to its original length if unloaded, but

will remain deformed 6. c. tends to return the material to its original size and shape 7. a. compression 8. b. tension

Chapter 3 1. c. composition of forces 2. b. resolution of forces 3. a. increases 4. b. increases the shearing component on L5S1 5. a. increases 6. b. concurrent 7. b. smaller 8. b. decreases 9. e. both b and c 10. c. 90 degrees 11. d. 90 degrees 12. b. decreases 13. a. increases 14. b. decreases 15. a. increases 16. a. increases



Chapter 4 1. b. ∑M = O 2. a. first class 3. c. third class 4. b. second class 5. c. third class 6. b. second class 7. d. For a movable pulley, less force is needed to move a load. 8. b. The line of muscle force is usually the greatest force of the forces involved to produce

the joint reaction force.

Chapter 5 1. d. more than 1 of the above 2. c. 30 lb 3. b. 0.25 4. d. 6 degrees 5. b. false

Chapter 6 1. b. increases 2. a. decreases 3. b. increases 4. c. centripetal force 5. b.TΘ 6. b. increases 7. b. less than 8. a. greater than 9. b. decreases it 10. a. increases flexion 11. d.s=rΘ

Chapter 7 1. b. up and backward 2. b. up and to the left 3. a. extended 4. c. it has a large base of support 5. c. at 90 degree flexion 6. b. further 7. b. longer 8. b. eccentric 9. a. concentric



shorT answer 1.

2. gravitational; inertial; contact; elastic; frictional; buoyant; muscular; electromagnetic (eddy currents)

3. strain 4. stress 5. fatigue 6. creep 7. resiliance 8. resultant 9. resolution 10. PFJF increase; PFJF decreases 11. (1)ΣF=0;(2)ΣM=0 12. (1) type of surface—coefficient of friction and (2) normal force 13. (1) force used to slide the object; (2) friction; and (3) component of weight parallel to the

ramp’s surface 14. (1) linear acceleration of the load and (2) angular acceleration of the limb 15. (1) mass and (2) radius from axis to the mass 16. increasing the mass of the object; increasing the area of the base; lowering the center of

mass of the object; keeping the center of mass directly over the center of the base 17. ability to discriminate; quantifiable; reliable; valid; standardized; ease of administration;

economy of time; availability of norms

ProBLems 1. H = 17.32 lb; V = 10 lb 2. F = 28.28 lb 3. A = 70.72 lb; B = 70.72 lb 4. PFJF = 422.6 lb



5. A) L = 20 lb B) A = 100 lb; B = 200 lb; F = 100 lb C) F = 173.2 lb 6. F = 50 lb; A = 100 lb 7. A = 90 lb; B = 30 lb 8. Moment = 86.6 ft•lb 9. A = 100 lb; B = 50 lb

a. clockwise b. clockwise around B; counterclockwise around A

10. M = 325 lb; J = 455 lb a. a. a clockwise

11. Moment = 1500 ft•lb 12. A = 45 lb; B = 60 lb 13. F=235lb;J=236.9lb;Θ=7.28degrees 14. M=57.7lb;J=49.3lb;Θ=54.2degrees 15. A = 26 lb; B = 13 lb; F = 13 lb 16. F = 13.83 lb 17. A = 15 lb; B = 30 lb; F = 15 lb 18. Ff = 30 lb

a. F = 30 lb b. d = 5 ft

19. F = 4 lb 20. Wx = 100 lb; Wy = 173.2 lb

a. up and right b. slide c. 134.64 lb

21. Θ=1.5rad;s=75cm;vA = 300 cm/sec 22. Θ=2.094rad;sH = 31.41 in; vH=157.05in/sec;ω=600degrees/sec;ω=10.47rad/sec 23. Θ=1.57rad;ω=10.47rad/sec;sA = 23.56 in; vA = 157 in/sec



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