Presentation on theme: "The Kinematics of Trauma"— Presentation transcript:
1The Kinematics of Trauma Physics, light on the math
2Axiomata sive leges motus Lex I: Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare.Lex II: Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum lineam rectam qua vis illa imprimitur.Lex III: Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi.
3Definitions and Simplifications DynamicsAn approach to physics that involves mathematical calculations to understand the motion of bodies. Answers are quantitative.KinematicsAn approach to physics that aims to understand the motion of bodies with minimal math. “Goldilocks physics”
4Definitions and Simplifications Mass=amount of matterForce=push or pullVelocity=distance/timeAcceleration=change in velocity/timeWeight=mass x gravitational accelerationEnergy=the ability to do work
5Definitions and Simplifications weight≈massDensity=mass/volumeHigher density=higher energy transfer
6Newton’s Laws of motion Objects in motion will stay in motion, and objects at rest will stay at rest unless acted on by an external force. (Inertia)
7Newton’s Laws of motion InertiaMeasured by an object’s momentumMomentum = mass x velocityUsed to describe an object’s resistance to changes in motion
8Newton’s Laws of motion An object’s acceleration is proportional to the force applied, and inversely proportional to its mass.(Force = mass x acceleration)Moving objects that are decelerated rapidly exert large forces
9Newton’s Laws of motion Every action has an equal and opposite reaction (forces exist in pairs)The reaction may cause further actionsForces can begin in a straight line, and disperse, causing cavitations
10Forces that cause trauma Compression (in-line)ContusionsPenetrationsLacerations(in combination with friction)DislocationsFractures
11Forces that cause trauma Torsion (rotational)DislocationsFractures
12Forces that cause trauma Friction (tangential)AbrasionsLacerations(in combination with compression)
13What injuries do you expect? Small group collaborationThink of as many injuries as you can.Compression Injuries?Torsion Injuries?Friction Injuries?Include type and locationExplain where the forces involved originated
14Pressure Pressure = Force / Area Pressure determines whether trauma is blunt or penetrating
15EnergyCan not be created or destroyed, only transferred or transformedTypes of EnergyThermalElectromagneticChemicalMechanical
16Injuries by energy type Electrical energy transforms into heat based on resistance to current flow.Heat energy does work on cells by denaturing proteins and vaporizing intracellular water.Chemical energy denatures proteins, and can transform into heat energy in the process.Mechanical energy does work on body structures by changing their position.
17Electromagnetic Energy Voltage is the “push” behind electricity.Current is the amount of electricity.Aside from the nervous system, the human body is not a good conductor.High resistance means lots of energy transformed into heat.
18Thermal Energy The human body is 70% water on average As water is changed to steam, it increases in volume 1700 timesProtein denaturing= irreversible changes in chemical structure.
19Chemical energy Most chemical burns are due to extreme pH. Acids donate protonsBases steal protonsToo many or too few protons leads to protein denaturation.
20Mechanical Energy Two components: kinetic and potential Kinetic is the energy of motion:Potential is stored energy due to height
21Energy RelationshipsIn any system, the mechanical energy is the sum of the potential and kinetic energies.Decreasing potential energy (falling) means increasing kinetic energy.
22Energy Relationships Work and Energy are equivalent Energy transfer W=EW=FdF=E/dEnergy transferRadiationConductionConvectionWork
23What’s it all mean? Since velocity is squared: Stopping distance: Doubling speed = 4x forceTripling speed = 9x forceStopping distance:Shorter distances mean greater forces
24Anatomical Concerns Most organs are not well secured within the body. Heart, kidneys and liver have massive blood supply
25Anatomic ConcernsSudden shifts can shear the vessels connected to these organsBlunt trauma to these organs can cause massive contusionsPenetrating trauma to these organs can cause life threatening loss of blood
26Anatomical Concerns Brain floats inside a boney cage A sudden shift stops the skull first, which then stops the brainVasculature on the surface of the brain is extensiveAs intracranial space fills with blood, where will it go?
28Anatomical Concerns Fragile body parts Lungs are only a single cell thickSudden impact can cause “paper bag” effectSpleen and liver covered only with a thin layer of connective tissueContusions and ruptures commonGI tract is a series of “bags”
29Anatomical Concerns Spinal curvature Forces can alter these curvatures Cervical and Sacral lordosisThoracic kyphosisForces can alter these curvatures
30Special Considerations Some situations may:Alter the normal mechanics of the bodyCause multiple phases of injury
31Pneumothorax Breathing is accomplished by creating “negative pressure” Diaphragm contracts, reducing the pressure in the chestAir rushes in to equalize the pressureHoles in the lung or chest wall allow air into the chest cavity, rather than the lung
32Blast Injuries Primary from absorbing the energy of the blast Secondary from being hit with flying objectsTertiary from being thrown against stationary objects
33Motor Vehicle Collisions Two systems of vehicle plus passengersTotal energy is the sum of the energies of the vehicles plus passengersEnergy is transferred from vehicle to vehicle, and between passengers and vehicles.
34Fall from height Longer falls mean more kinetic energy Terminal velocity reached at about 60 ft.Elastic surfaces will absorb some of the energy of the falling personInelastic surfaces cause ALL of the energy of the fall to be absorbed by the body
35Please email your answers to: QUIZ!Let’s see what stuck.Please your answers to:
36Question 1How many laws of motion did Isaac Newton posit?
37Question 2 Which object has greater momentum? A speeding bullet A fully loaded ambulance at 10 mph
38Question 3List a type of injury that could be caused by each of the following:Compressional ForceTorsional ForceFrictional Force
39Question 4Which of the following is true regarding the magnitude of the forces involved in a vehicle collision?The mass of the vehicle is more important than the speedThe mass of the vehicle is less important than the speedThe area of collision matters the mostAirbag deployment matters the most
40Question 5 Which seatbelt will reduce the force of impact best? A seatbelt that does not flexA flexible seatbelt that stretches slightlyNo seatbelt
41Question 6What are the three causes of injury from explosions?
42Question 7How is it possible for electricity to cause burns?
43Question 8What determines whether an injury will be blunt or penetrating?
44Question 9Energy cannot be __________________ or ___________________, only ________________ or ______________.
45Question 10Why are motor vehicle collisions so damaging to the human body?