Quiz 2

Question 1

Describe inertia

Answer 1

The ability of an object to resist change (continuous movement)

(Note: The greater the mass, the greater the inertia)

Question 2

What is “moment of inertia”?

Answer 2

The ability of an object to resist change in an angular movement

Question 3

Describe the Law of Action-Reaction

Answer 3

For every action, there is always an equal (and opposite) reaction

(ex: if you punch a wall, it punches you back)

Question 4

What does Newton’s 1st Law state?

Answer 4

The greater the mass, the greater the inertia (Law of Inertia)

Question 5

What does Newton’s 2nd Law state?

Answer 5

Nothing… just know that it is the Law of Acceleration

Question 6

What does Newton’s 3rd Law state?

Answer 6

For every action there is always an equal and opposite reaction (Law of Action-Reaction)

Question 7

What are the 3 things to consider when looking at force?

Answer 7

1. Axis of rotation
2. Resistance (Gravity or weight)
3. effort

Question 8

Describe “torque”

Answer 8

“Torque” is the angular term for “force”

Question 9

Describe “moment arm”

Answer 9

The perpendicular distance from the axis of rotation to the force vector

Question 10

Differentiate between the 3 classes of levers

Answer 10

Class 1 Lever: Axis of rotation is in between the resistance and effort

Class 2 Lever: Resistance is in between the axis of rotation and effort (mechanical advantage)

Class 3 Lever: Effort is located between the axis of rotation and resistance
(excursion advantage)

Question 11

Differentiate between vector and scalar

Answer 11

Vector: Must contain direction and magnitude
- Force, weight, velocity, displacement

Scalar: Contains magnitude but no direction
- Mass, speed, distance

Question 12

How to calculate momentum?

Answer 12

Mass*Velocity

Question 13

Describe “impulse” momentum

Answer 13

The force that provides resistance to momentum

• Can be used concentrically to generate impulse
• Can be used eccentrically to go against momentum

Question 14

Differentiate between potential and kinetic energy

Answer 14

Potential Energy: Energy due to it’s position

Kinetic Energy: Energy due to motion

Question 15

T or F? Energy can never destroyed

Answer 15

True

Question 16

What is power?

Answer 16

Moving a heavy weight as fast as possible

Question 17

Differentiate between the two types of bone

Answer 17

Cortical Bone: Dense and forms the outer layer of a bone segment

Trabecular Bone: Low density and fills the inside of a bone segment

Question 18

What are the 6 types of bone fractures?

Answer 18

• Compression Fracture (caused by compression)
• Tension Fracture (caused by pulling at both ends of the bone segment)
• Bending Fracture (caused by bending of the bone segment)
• Shear Fracture (caused by two forces going opposite directions… one force moves the upper part of the bone one way and one force moves the lower part of the bone the other way)
• Torsion Fracture (caused by twisting of the bone segment)
• Combined Loading Fracture [caused by compression and torsion (twisting) of a bone segment]

Question 19

How do you strengthen a bone?

Answer 19

Weight bearing exercises

(Supported by Wolff’s Law: “If loading on a particular bone increases, the bone will remodel itself over time to become stronger to resist that sort of loading)

Question 20

How is “stiffness” determined?

Answer 20

• The force that acts on an object (stress)
• The shape of the object (strain)

ex: An object is considered stiff if a large amount of force can only cause a small change of shape

Question 21

What are the 3 types of joints?

Answer 21

Synarthrosis: Joints that can barely move (skull)
Amphiarthrosis: Joints that can slightly move
Diarthrosis: Joints that can move freely with a certain amount of “degrees of freedom”

Degrees of Freedom (DOF): The number of axis that the joint can move around

Question 22

What are the 6 types of joints?

Answer 22

• Plane Joint
• Hinge Joint
• Pivot Joint
• Saddle Joint
• Condyloid Joint
• Ball and Socket Joint

Question 23

Differentiate between a close-packed and loose-packed joint position?

Answer 23

Closed-packed: Joint space is minimized

Loose-packed: Joint space is maximized

Question 24

What are the 3 types of muscle fibers and their function?

Answer 24

Type I: Slow-twitch oxidative fibers
- High endurance, low power

Type IIa: Fast-twitch oxidative fibers
- Intermediate power and endurance

Type IIb: Fast-twitch gylcolytic fibers
- High power, low endurance

Question 25

T or F? Posture muscles are more type I whereas power muscles are more type II

Answer 25

True

Question 26

T or F? Atrophy is greater in type II muscle fibers than it is in type I

Answer 26

True

Question 27

How do muscle neuromechanics work? provide an example

Answer 27

Alpha motor neurons send a signal to an axon, and the axon carries the signal to innervate muscle fibers

ex: flicking a light switch on, the current traveling through the wires, then eventually turning the lights on

Question 28

T or F? Small size motor units control type I muscle fibers, medium size motor units control type IIa, large size motor units control type IIb muscle fibers

Answer 28

True

Question 29

What does the henneman’s principle state? What is the benefit of it?

Answer 29

Motor units are recruited from smallest to largest (this helps preserve energy)

Question 30

Explain the roll and slide of…
- convex on concave
- concave on convex

Answer 30

Convex on Concave: Roll and slide are opposite

Concave on Convex: Roll and slide are same

Question 31

What is force decomposition?

Answer 31

When you see a muscle in oblique orientation, readjust it to horizontal and vertical components