Lecture 18

Question 1

What is whole body center of mass located on the body

Answer 1

Approx just in front of lumbosacral junction in standing posture

May move outside the body

Question 2

What is center of gravity

Answer 2

The point through which the force of gravity acts on an object or system

Question 3

COM and COG have the same…

Answer 3

Position

Question 4

Tissue mechanics focuses on

Answer 4

Bones
Ligaments
Cartilage
Tendons

Question 5

What is a load

Answer 5

An externally applied force

Question 6

What are the different types of loading

Answer 6

Axial

Bending

Shear

Question 7

What is axial loading

Answer 7

Loading acts along longitudinal axis of a body

Question 8

What is involved in axial loading

Answer 8

Compression

Tension

Question 9

What is compression

Answer 9

A load that squeezes the parts of a body together

Question 10

What is tension

Answer 10

A load that pulls the parts of a body apart

Question 11

What is bending loading

Answer 11

A load applied perpendicular to the longitudinal axis of a body causing a body to curve

Question 12

What is involved in bending

Answer 12

Three point bending

Four point bending

Question 13

What is three point bending

Answer 13

Three forces applied

Question 14

What is four point bending

Answer 14

Four forces applied

Question 15

What is the effect of bending determined by

Answer 15

Cross section area

Length of body

Distribution of the material around the neutral axis

Question 16

What is area moment of inertia

Answer 16

Combined effect of cross section area and how it is distributed from the neutral axis

A measure of the bodys resistance to bending

Question 17

During bending what loading occurs on one side and what loading on the other side

Answer 17

Tensile loading on one side

Compressive loading on the other

Question 18

What is shear loading

Answer 18

Two forces are directed towards each other

But the forces are not along the same line and instead they are directed parallel to the surface of a structure

Question 19

What does shearing cause to happen to an object

Answer 19

Two surfaces to move in opposite parallel directions

Causes one part of the body to move parallel past another part

Question 20

What is Shear loading broken up into

Answer 20

Direct

Torsion

Question 21

What is torsional loading

Answer 21

Loads that exists when there is a twist around the neutral axis

Question 22

What is stress

What is the equation

What is the unit

Answer 22

The way a force is distributed within a body

Force / area

Unit N/m^2

Question 23

What is strain

Answer 23

The change in dimension normalized to the original dimension

Question 24

What is the equation of strain

Answer 24

Change in dimension / original dimension

Question 25

What is the equation for elastic modulus

Answer 25

Stress / strain

Question 26

What is strain energy

Answer 26

The amount of energy that the body can absorb as it deformed

Question 27

What is strain energy density

Answer 27

The amount of energy that can be absorbed by a normalised piece of tissue

Question 28

What is bones function

Answer 28

Provides a rigid framework that gives body shape Functions as a set of rigid links and mechanical levers Provides attachment sites for muscle tendon complexes Protects the CNS and various internal organs

Question 29

What is bone mineral content

Answer 29

Total amount of mineral in bone

Question 30

What is bone mineral density

Answer 30

The mineral content in an area or volume of bone

Question 31

Overall strength of the bone is affected by

Answer 31

Bone mineral density Where the bone is placed

Question 32

Bone is considered... Why

Answer 32

Asymmetric Bone is stronger in compression vs tension Bone is stronger in tension vs shear

Question 33

Males have greater... (bone)

Answer 33

Peak bone mass Rate of gain for bone mineral content

Question 34

Females have... (bone)

Answer 34

Transient decrease in bone mass around the menopause age of 45 - 60

Question 35

Bone is a what tissue

Answer 35

Dynamic

Question 36

Disuse and aging have what effect on bones

Answer 36

Inverse relationship with bone health

Question 37

Exercise has what effect on bones

Answer 37

Beneficial effect on mechanical properties of bone

Question 38

Weight bearing exercise has what effect on bones

Answer 38

Direct relationship with bone health

Question 39

Exercise should be: (in order to help bone health)

Answer 39

Dynamic loading Moderate to high loading rate Short duration Long rest periods - allows tissue adaptation to new load