Biomechanics

Question 1

what does “bio” refer to?

Answer 1

life/living organisms

Question 2

what does “mechanics” refer to?

Answer 2

study of physical actions of forces

Question 3

define statics

Answer 3

the study of systems in a constant state of motion

Question 4

define dynamics

Answer 4

the study of systems in motion with acceleration

Question 5

define kinematics

Answer 5

description of a systems motion

Question 6

define kinetics

Answer 6

study of forces associated with a body’s motion

Question 7

what are the key functions of machines?

Answer 7

• increase mechanical advantage
• balances multiple forces
• enhances forces to decrease the total force required to overcome resistance
• enhance ROM and speed of movement to move resistance further or faster than the applied force
• alter the resulting direction of the applied force

Question 8

what are the different kinds of machines?

Answer 8

• levers
• wheel and axle
• pulleys

Question 9

describe what a lever machine is

Answer 9

most common type of machine that allows the body to move and apply force.
- 1st, 2nd, and 3rd classes

Question 10

define 1st class levers

Answer 10

effort and load are on opposite sides of the fulcrum - ex: triceps extension

Question 10

define 2nd class levers

Answer 10

effort and load are on the same side of the fulcrum; effort is farther from fulcrum and load is closer
- ex: calf raise

Question 11

define 3rd class levers

Answer 11

effort and load are on the same side of the fulcrum; effort is closer to the fulcrum and load is farther
- ex: elbow flexion

Question 12

define torque

Answer 12

an eccentric force that causes rotation
- Eccentric force: muscle contraction pulling on bones at attachment sites causing bones to rotate at joint axis

Question 13

describe what a wheel and axle machine is

Answer 13

• Purpose: enhance ROM and speed
• Function: 1st class lever; wheel and axle complete turn at the same time
• Mechanical advantage: determined by the radius of the wheel compared to the radius of the axle

Question 14

describe what a pulley machine is

Answer 14

• Purpose: change effective direction of force application
• Function: single, compound

Question 15

what is an example of a wheel and axle machine in the body?

Answer 15

axle = humerus
Outside of wheel = hand/wrist
Movement = internal rotation
Results = increased speed to throw objects

Question 16

what is an example of a pulley machine in the body?

Answer 16

Pulley = lateral malleolus
Tendon = peroneus longus
Movement = ankle PF, eversion

Question 17

describe Newton’s 1st law of motion: Inertia

Answer 17

an object at rest remains at rest and an object in motion remains in motion at a constant speed and in a straight line unless acted on by an unbalanced force

Question 18

describe Newton’s 2nd law of motion: Force

Answer 18

acceleration of an object depends on its mass and the amount of force applied; F=MA

Question 19

describe Newton’s 3rd law of motion: Action/reaction

Answer 19

for every action, there is an equal and opposite reaction

Question 20

define static friction

Answer 20

resultant force from resistance between 2 object surfaces coming into contact AT REST

Question 21

define kinetic friction

Answer 21

resultant force from resistance between 2 object surfaces coming into contact
SLIDING against each other

Question 22

define rolling friction

Answer 22

resultant force from resistance between 2 object surfaces coming into contact
ROLLING across a surface

Question 23

define balance

Answer 23

ability to control equilibrium
- Equilibrium: state of 0 acceleration
- Stability: needed to control equilibrium and achieve balance

Question 24

how is stability achieved?

Answer 24

• enhanced by altering COG as needed
• COG: the point at which all of the body’s mass and weight are equally distributed
• Response to perturbation: lower COG, COG within BOS, and enlarged BOS

Question 25

what is the number 1 source of force?

Answer 25

• Muscle contraction is the number 1 source of force
• Without forces there is no movement
• F=MA (force = mass times acceleration)

Question 26

what is the momentum equation?

Answer 26

M=MV (momentum = mass times velocity)
- Impulse = force x time (can alter momentum)

Question 27

describe what a mechanical load is

Answer 27

physical stress on a mechanical system or component

Question 28

what are some internal and external forces effecting mechanical load?

Answer 28

Internal forces:
- Active: muscle contraction
- Passive: tension in tendons,
connective tissues,
ligaments, and joint
capsules
External forces:
- Gravity
- Inertia
- Direct contact

Question 29

what are the different types of mechanical load?

Answer 29

• Tension (stretch/strain)
• Compression
• Shear
• Bending
• Torsion (twist)
• Combined (compression + rotation)

Question 30

describe some injuries and prevention associated with mechanical loads

Answer 30

injury/damage:
- Fracture bones
- Dislocate joints
- Disrupt muscles and
connective tissues

Injury prevention
- The body can absorb
energy from internal and
external forces
- Absorb force over larger
aspects
- Spread absorption rate over
a greater time period
- Stronger and healthier
tissue can withstand greater
mechanical loading