Intro: Laws, levers, planes, axes

Question 1

Biomechanics

Answer 1

the application of classical mechanics to the analysis of biological and physiological systems

Question 2

Axis and Coordinate Systems

Answer 2

Y is positive upward, X is positive anteriorly, Z is positive to the person’s right

Question 3

Frontal Plane

Answer 3

formed by vertical (y) and mediolateral (z) axes; rotates about the anteroposterior (x) axis;

actions: A24, A44; lat bend

Question 4

Sagittal Plane

Answer 4

formed by vertical (y) and anteroposterior (x) axes; rotates about mediolateral (z) axis

actions: flexion/extension

Question 5

Transverse Plane

Answer 5

formed by the anteroposterior (x) and mediolateral (z) axes; rotates about the vertical (y) axis

actions: rotation

Question 6

Kinematics

Answer 6

description of motion; displacement, velocity, acceleration, angular displacement/velocity/acceleration

Question 7

Kinetics

Answer 7

description of forces; force and moment

Question 8

External Forces

Answer 8

forces acting ON the body; force due to gravity, an external load, etc.

Question 9

Internal Forces

Answer 9

forces acting INSIDE the body; could be a force produced by the muscle, passive constraint such as ligament or joint capsule

Question 10

Moment Arm

Answer 10

perpendicular distance between line of action of the force and axis of rotation

Question 11

Scalar Quantities

Answer 11

have direction only; can be positive or negative; add algebraically (only those with the same units); mass, distance, speed

Question 12

Vector Quantities

Answer 12

have magnitude AND direction; usually noted with an arrow or underline; add by parallelogram method or law of cosines

Question 13

Center of Mass

Answer 13

point at which the entire mass of an object can be considered to be located;

Question 14

Base of Support and Stability

Answer 14

to increase stability, increase BOS area or move COM closer to the BOS

to decrease stability, decrease BOS area or move COM farther from the BOS

Question 15

Center of Gravity

Answer 15

balance point for an object; location (given as coordinates)

Question 16

Newton’s First Law: Law of Inertia

Answer 16

an object at rest will stay at rest, unless acted on by an unbalanced external force;

An object in motion will stay in motion unless acted on

Static equilibrium: sum of forces = 0

Question 17

Newton’s Second Law: Law of Acceleration

Answer 17

acceleration is produced when a force acts on a mass (F=ma)

larger mass requires larger force to accelerate or decelerate

Question 18

Newton’s Third Law: Law of Reaction

Answer 18

for every action there is an equal and opposite reaction;

reaction force acts in the opposite direction along the same line of action as the action force

Question 19

Translational Motion

Answer 19

forces acting at one location; could be a colinear system (tug of war), concurrent force, or pulley force system

Question 20

First Class Lever

Answer 20

“see-saw”; external force (load) and internal force (muscle) on opposite sides of fulcrum;

Ex: head

Question 21

Second Class Lever

Answer 21

“wheelbarrow”; fulcrum and internal force (muscle) on opposite sides of the external force (load); MA muscle > MA external

Great mechanical advantage- can lift very heavy loads through short distances

Ex: toe raise

Question 22

Third Class Levers

Answer 22

fulcrum and external force on opposite sides of the internal force; MAmuscle