The Kinematics of Trauma Physics, light on the math.

The Kinematics of TraumaThe Kinematics of Trauma

Physics, light on the mathPhysics, light on the math

Axiomata sive leges motusAxiomata sive leges motus Lex I: Corpus omne perseverare in statu suo Lex I: Corpus omne perseverare in statu suo

quiescendi vel movendi uniformiter in quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis directum, nisi quatenus a viribus impressis cogitur statum illum mutare.cogitur statum illum mutare.

Lex II: Mutationem motus proportionalem Lex II: Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum esse vi motrici impressae, et fieri secundum lineam rectam qua vis illa imprimitur.lineam rectam qua vis illa imprimitur.

Lex III: Actioni contrariam semper et Lex III: Actioni contrariam semper et æqualem esse reactionem: sive corporum æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi.æquales et in partes contrarias dirigi.

Definitions and Definitions and SimplificationsSimplifications

DynamicsDynamics An approach to physics that involves An approach to physics that involves

mathematical calculations to understand the mathematical calculations to understand the motion of bodies. Answers are quantitative.motion of bodies. Answers are quantitative.

KinematicsKinematics An approach to physics that aims to An approach to physics that aims to

understand the motion of bodies with understand the motion of bodies with minimal math. “Goldilocks physics”minimal math. “Goldilocks physics”


Mass=amount of matter Mass=amount of matter Force=push or pullForce=push or pull Velocity=distance/time Velocity=distance/time Acceleration=change in velocity/timeAcceleration=change in velocity/time Weight=mass x gravitational Weight=mass x gravitational

accelerationacceleration Energy=the ability to do workEnergy=the ability to do work


weightweight≈mass≈mass Density=mass/volumeDensity=mass/volume

Higher density=higher energy transferHigher density=higher energy transfer

Newton’s Laws of motionNewton’s Laws of motion

Objects in motion will stay in motion, Objects in motion will stay in motion, and objects at rest will stay at rest and objects at rest will stay at rest unless acted on by an external force. unless acted on by an external force. (Inertia)(Inertia)


InertiaInertia Measured by an object’s momentumMeasured by an object’s momentum

Momentum = mass x velocityMomentum = mass x velocity Used to describe an object’s resistance Used to describe an object’s resistance

to changes in motionto changes in motion


An object’s acceleration is An object’s acceleration is proportional to the force applied, and proportional to the force applied, and inversely proportional to its mass. inversely proportional to its mass.

(Force = mass x acceleration)(Force = mass x acceleration) Moving objects that are decelerated Moving objects that are decelerated

rapidly exert large forcesrapidly exert large forces


Every action has an equal and Every action has an equal and opposite reaction (forces exist in opposite reaction (forces exist in pairs)pairs) The reaction may cause further actionsThe reaction may cause further actions

Forces can begin in a straight line, Forces can begin in a straight line, and disperse, causing cavitationsand disperse, causing cavitations

Forces that cause traumaForces that cause trauma

Compression (in-line)Compression (in-line) ContusionsContusions PenetrationsPenetrations Lacerations(in combination with friction)Lacerations(in combination with friction)

DislocationsDislocations FracturesFractures


Torsion (rotational)Torsion (rotational) DislocationsDislocations FracturesFractures


Friction (tangential)Friction (tangential) AbrasionsAbrasions Lacerations(in combination with Lacerations(in combination with

compression)compression)

What injuries do you What injuries do you expect?expect?

Small group collaborationSmall group collaboration Think of as many injuries as you can.Think of as many injuries as you can. Compression Injuries?Compression Injuries? Torsion Injuries?Torsion Injuries? Friction Injuries?Friction Injuries?

Include type and locationInclude type and location Explain where the forces involved Explain where the forces involved

originatedoriginated

PressurePressure

Pressure = Force / AreaPressure = Force / Area Pressure determines whether trauma Pressure determines whether trauma

is blunt or penetratingis blunt or penetrating

EnergyEnergy

Can not be created or destroyed, Can not be created or destroyed, only transferred or transformedonly transferred or transformed

Types of EnergyTypes of Energy ThermalThermal ElectromagneticElectromagnetic ChemicalChemical MechanicalMechanical

Injuries by energy typeInjuries by energy type

Electrical energy transforms into heat based Electrical energy transforms into heat based on resistance to current flow.on resistance to current flow.

Heat energy does work on cells by Heat energy does work on cells by denaturing proteins and vaporizing denaturing proteins and vaporizing intracellular water.intracellular water.

Chemical energy denatures proteins, and can Chemical energy denatures proteins, and can transform into heat energy in the process.transform into heat energy in the process.

Mechanical energy does work on body Mechanical energy does work on body structures by changing their position.structures by changing their position.

Electromagnetic EnergyElectromagnetic Energy

Voltage is the “push” behind Voltage is the “push” behind electricity.electricity.

Current is the amount of electricity.Current is the amount of electricity. Aside from the nervous system, the Aside from the nervous system, the

human body is not a good conductor.human body is not a good conductor. High resistance means lots of energy High resistance means lots of energy

transformed into heat.transformed into heat.

Thermal EnergyThermal Energy

The human body is 70% water on The human body is 70% water on averageaverage

As water is changed to steam, it As water is changed to steam, it increases in volume 1700 timesincreases in volume 1700 times

Protein denaturing= irreversible Protein denaturing= irreversible changes in chemical structure.changes in chemical structure.

Chemical energyChemical energy

Most chemical burns are due to Most chemical burns are due to extreme pH.extreme pH. Acids donate protonsAcids donate protons Bases steal protonsBases steal protons

Too many or too few protons leads to Too many or too few protons leads to protein denaturation.protein denaturation.

Mechanical EnergyMechanical Energy

Two components: kinetic and potentialTwo components: kinetic and potential Kinetic is the energy of motion:Kinetic is the energy of motion:

Potential is stored energy due to heightPotential is stored energy due to height

heightgravitymass

2

2velocitymass

Energy RelationshipsEnergy Relationships

In any system, the mechanical In any system, the mechanical energy is the sum of the potential energy is the sum of the potential and kinetic energies.and kinetic energies. Decreasing potential energy (falling) Decreasing potential energy (falling)

means increasing kinetic energy.means increasing kinetic energy.

Energy RelationshipsEnergy Relationships

Work and Energy are equivalentWork and Energy are equivalent W=EW=E W=FdW=Fd F=E/dF=E/d

Energy transferEnergy transfer RadiationRadiation ConductionConduction ConvectionConvection WorkWork

What’s it all mean?What’s it all mean?

Since velocity is Since velocity is squared:squared: Doubling speed = Doubling speed =

4x force4x force Tripling speed = 9x Tripling speed = 9x

forceforce Stopping distance:Stopping distance:

Shorter distances Shorter distances mean greater mean greater forcesforces

0

1000

2000

3000

4000

5000

6000

7000

1 5 10 20 40 80

Speed

Kin

etic

Energ

y

0

5

10

15

20

25

30

35

100 50 25 12 6 3

Stopping distance

Forc

e ex

erte

d

Anatomical ConcernsAnatomical Concerns

Most organs are not well secured Most organs are not well secured within the body.within the body. Heart, kidneys and liver have massive Heart, kidneys and liver have massive

blood supplyblood supply

Anatomic ConcernsAnatomic Concerns

Sudden shifts can shear the vessels Sudden shifts can shear the vessels connected to these organsconnected to these organs

Blunt trauma to these organs can Blunt trauma to these organs can cause massive contusionscause massive contusions

Penetrating trauma to these organs Penetrating trauma to these organs can cause life threatening loss of can cause life threatening loss of bloodblood


Brain floats inside a boney cageBrain floats inside a boney cage A sudden shift stops the skull first, which A sudden shift stops the skull first, which

then stops the brainthen stops the brain Vasculature on the surface of the brain Vasculature on the surface of the brain

is extensiveis extensive As intracranial space fills with blood, As intracranial space fills with blood,

where will it go?where will it go?

Brain VasculatureBrain Vasculature


Fragile body partsFragile body parts Lungs are only a single cell thickLungs are only a single cell thick

Sudden impact can cause “paper bag” effectSudden impact can cause “paper bag” effect Spleen and liver covered only with a thin Spleen and liver covered only with a thin

layer of connective tissue layer of connective tissue Contusions and ruptures commonContusions and ruptures common

GI tract is a series of “bags”GI tract is a series of “bags”


Spinal curvatureSpinal curvature Cervical and Cervical and

Sacral lordosisSacral lordosis Thoracic Thoracic

kyphosiskyphosis Forces can alter Forces can alter

these these curvaturescurvatures

Special ConsiderationsSpecial Considerations

Some situations may:Some situations may: Alter the normal mechanics of the bodyAlter the normal mechanics of the body Cause multiple phases of injuryCause multiple phases of injury

PneumothoraxPneumothorax

Breathing is accomplished by creating Breathing is accomplished by creating “negative pressure”“negative pressure”

Diaphragm contracts, reducing the Diaphragm contracts, reducing the pressure in the chestpressure in the chest

Air rushes in to equalize the pressureAir rushes in to equalize the pressure Holes in the lung or chest wall allow Holes in the lung or chest wall allow

air into the chest cavity, rather than air into the chest cavity, rather than the lungthe lung

Blast InjuriesBlast Injuries

Primary from absorbing the energy of Primary from absorbing the energy of the blastthe blast

Secondary from being hit with flying Secondary from being hit with flying objectsobjects

Tertiary from being thrown against Tertiary from being thrown against stationary objectsstationary objects

Motor Vehicle CollisionsMotor Vehicle Collisions

Two systems of vehicle plus Two systems of vehicle plus passengerspassengers

Total energy is the sum of the Total energy is the sum of the energies of the vehicles plus energies of the vehicles plus passengerspassengers

Energy is transferred from vehicle to Energy is transferred from vehicle to vehicle, and between passengers vehicle, and between passengers and vehicles.and vehicles.

Fall from heightFall from height

Longer falls mean more kinetic Longer falls mean more kinetic energyenergy Terminal velocity reached at about 60 ft.Terminal velocity reached at about 60 ft.

Elastic surfaces will absorb some of Elastic surfaces will absorb some of the energy of the falling personthe energy of the falling person

Inelastic surfaces cause ALL of the Inelastic surfaces cause ALL of the energy of the fall to be absorbed by energy of the fall to be absorbed by the bodythe body

QUIZ!QUIZ!

Let’s see what stuck.Let’s see what stuck.

Please email your answers to:Please email your answers to:

[email protected]@sheridanmemorial.net

Question 1Question 1

How many laws of motion did Isaac How many laws of motion did Isaac Newton posit?Newton posit?


Which object has greater Which object has greater momentum?momentum?

A speeding bulletA speeding bullet A fully loaded ambulance at 10 mphA fully loaded ambulance at 10 mph


List a type of injury that could be List a type of injury that could be caused by each of the following:caused by each of the following:

Compressional ForceCompressional Force Torsional ForceTorsional Force Frictional ForceFrictional Force


Which of the following is true Which of the following is true regarding the magnitude of the regarding the magnitude of the forces involved in a vehicle collision?forces involved in a vehicle collision?

A.A. The mass of the vehicle is more The mass of the vehicle is more important than the speedimportant than the speed

B.B. The mass of the vehicle is less The mass of the vehicle is less important than the speedimportant than the speed

C.C. The area of collision matters the mostThe area of collision matters the mostD.D. Airbag deployment matters the mostAirbag deployment matters the most


Which seatbelt will reduce the force Which seatbelt will reduce the force of impact best?of impact best?

A.A. A seatbelt that does not flexA seatbelt that does not flex

B.B. A flexible seatbelt that stretches A flexible seatbelt that stretches slightlyslightly

C.C. No seatbeltNo seatbelt


What are the three causes of injury What are the three causes of injury from explosions? from explosions?


How is it possible for electricity to How is it possible for electricity to cause burns? cause burns?


What determines whether an injury What determines whether an injury will be blunt or penetrating?will be blunt or penetrating?


Energy cannot be __________________ Energy cannot be __________________ or ___________________, only or ___________________, only ________________ or ______________.________________ or ______________.


Why are motor vehicle collisions so Why are motor vehicle collisions so damaging to the human body?damaging to the human body?

Please email your answers Please email your answers to: to:

[email protected]@sheridanmemorial.netnet

The Kinematics of Trauma Physics, light on the math.

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