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The Kinematics of Trauma Physics, light on the math.

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1 The Kinematics of Trauma Physics, light on the math

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

3 Definitions and Simplifications Dynamics Dynamics An approach to physics that involves mathematical calculations to understand the motion of bodies. Answers are quantitative. An approach to physics that involves mathematical calculations to understand the motion of bodies. Answers are quantitative. Kinematics Kinematics An approach to physics that aims to understand the motion of bodies with minimal math. Goldilocks physics An approach to physics that aims to understand the motion of bodies with minimal math. Goldilocks physics

4 Definitions and Simplifications Mass=amount of matter Mass=amount of matter Force=push or pull Force=push or pull Velocity=distance/time Velocity=distance/time Acceleration=change in velocity/time Acceleration=change in velocity/time Weight=mass x gravitational acceleration Weight=mass x gravitational acceleration Energy=the ability to do work Energy=the ability to do work

5 Definitions and Simplifications weightmass weightmass Density=mass/volume Density=mass/volume Higher density=higher energy transfer Higher density=higher energy transfer

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

7 Newtons Laws of motion Inertia Inertia Measured by an objects momentum Measured by an objects momentum Momentum = mass x velocity Momentum = mass x velocity Used to describe an objects resistance to changes in motion Used to describe an objects resistance to changes in motion

8 Newtons Laws of motion An objects acceleration is proportional to the force applied, and inversely proportional to its mass. An objects 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 Moving objects that are decelerated rapidly exert large forces

9 Newtons Laws of motion Every action has an equal and opposite reaction (forces exist in pairs) Every action has an equal and opposite reaction (forces exist in pairs) The reaction may cause further actions The reaction may cause further actions Forces can begin in a straight line, and disperse, causing cavitations Forces can begin in a straight line, and disperse, causing cavitations

10 Forces that cause trauma Compression (in-line) Compression (in-line) Contusions Contusions Penetrations Penetrations Lacerations(in combination with friction) Lacerations(in combination with friction) Dislocations Dislocations Fractures Fractures

11 Forces that cause trauma Torsion (rotational) Torsion (rotational) Dislocations Dislocations Fractures Fractures

12 Forces that cause trauma Friction (tangential) Friction (tangential) Abrasions Abrasions Lacerations(in combination with compression) Lacerations(in combination with compression)

13 What injuries do you expect? Small group collaboration Small 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 location Include type and location Explain where the forces involved originated Explain where the forces involved originated

14 Pressure Pressure = Force / Area Pressure = Force / Area Pressure determines whether trauma is blunt or penetrating Pressure determines whether trauma is blunt or penetrating

15 Energy Can not be created or destroyed, only transferred or transformed Can not be created or destroyed, only transferred or transformed Types of Energy Types of Energy Thermal Thermal Electromagnetic Electromagnetic Chemical Chemical Mechanical Mechanical

16 Injuries by energy type Electrical energy transforms into heat based on resistance to current flow. Electrical energy transforms into heat based on resistance to current flow. Heat energy does work on cells by denaturing proteins and vaporizing intracellular water. 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. Chemical energy denatures proteins, and can transform into heat energy in the process. Mechanical energy does work on body structures by changing their position. Mechanical energy does work on body structures by changing their position.

17 Electromagnetic Energy Voltage is the push behind electricity. Voltage is the push behind electricity. Current is the amount of electricity. Current is the amount of electricity. Aside from the nervous system, the human body is not a good conductor. Aside from the nervous system, the human body is not a good conductor. High resistance means lots of energy transformed into heat. High resistance means lots of energy transformed into heat.

18 Thermal Energy The human body is 70% water on average The human body is 70% water on average As water is changed to steam, it increases in volume 1700 times As water is changed to steam, it increases in volume 1700 times Protein denaturing= irreversible changes in chemical structure. Protein denaturing= irreversible changes in chemical structure.

19 Chemical energy Most chemical burns are due to extreme pH. Most chemical burns are due to extreme pH. Acids donate protons Acids donate protons Bases steal protons Bases steal protons Too many or too few protons leads to protein denaturation. Too many or too few protons leads to protein denaturation.

20 Mechanical Energy Two components: kinetic and potential Two components: kinetic and potential Kinetic is the energy of motion: Kinetic is the energy of motion: Potential is stored energy due to height Potential is stored energy due to height

21 Energy Relationships In any system, the mechanical energy is the sum of the potential and kinetic energies. In any system, the mechanical energy is the sum of the potential and kinetic energies. Decreasing potential energy (falling) means increasing kinetic energy. Decreasing potential energy (falling) means increasing kinetic energy.

22 Energy Relationships Work and Energy are equivalent Work and Energy are equivalent W=E W=E W=Fd W=Fd F=E/d F=E/d Energy transfer Energy transfer Radiation Radiation Conduction Conduction Convection Convection Work Work

23 Whats it all mean? Since velocity is squared: Since velocity is squared: Doubling speed = 4x force Doubling speed = 4x force Tripling speed = 9x force Tripling speed = 9x force Stopping distance: Stopping distance: Shorter distances mean greater forces Shorter distances mean greater forces

24 Anatomical Concerns Most organs are not well secured within the body. Most organs are not well secured within the body. Heart, kidneys and liver have massive blood supply Heart, kidneys and liver have massive blood supply

25 Anatomic Concerns Sudden shifts can shear the vessels connected to these organs Sudden shifts can shear the vessels connected to these organs Blunt trauma to these organs can cause massive contusions Blunt trauma to these organs can cause massive contusions Penetrating trauma to these organs can cause life threatening loss of blood Penetrating trauma to these organs can cause life threatening loss of blood

26 Anatomical Concerns Brain floats inside a boney cage Brain floats inside a boney cage A sudden shift stops the skull first, which then stops the brain A sudden shift stops the skull first, which then stops the brain Vasculature on the surface of the brain is extensive Vasculature on the surface of the brain is extensive As intracranial space fills with blood, where will it go? As intracranial space fills with blood, where will it go?

27 Brain Vasculature

28 Anatomical Concerns Fragile body parts Fragile body parts Lungs are only a single cell thick Lungs are only a single cell thick Sudden impact can cause paper bag effect Sudden impact can cause paper bag effect Spleen and liver covered only with a thin layer of connective tissue Spleen and liver covered only with a thin layer of connective tissue Contusions and ruptures common Contusions and ruptures common GI tract is a series of bags GI tract is a series of bags

29 Anatomical Concerns Spinal curvature Spinal curvature Cervical and Sacral lordosis Cervical and Sacral lordosis Thoracic kyphosis Thoracic kyphosis Forces can alter these curvatures Forces can alter these curvatures

30 Special Considerations Some situations may: Some situations may: Alter the normal mechanics of the body Alter the normal mechanics of the body Cause multiple phases of injury Cause multiple phases of injury

31 Pneumothorax Breathing is accomplished by creating negative pressure Breathing is accomplished by creating negative pressure Diaphragm contracts, reducing the pressure in the chest Diaphragm contracts, reducing the pressure in the chest Air rushes in to equalize the pressure Air rushes in to equalize the pressure Holes in the lung or chest wall allow air into the chest cavity, rather than the lung Holes in the lung or chest wall allow air into the chest cavity, rather than the lung

32 Blast Injuries Primary from absorbing the energy of the blast Primary from absorbing the energy of the blast Secondary from being hit with flying objects Secondary from being hit with flying objects Tertiary from being thrown against stationary objects Tertiary from being thrown against stationary objects

33 Motor Vehicle Collisions Two systems of vehicle plus passengers Two systems of vehicle plus passengers Total energy is the sum of the energies of the vehicles plus passengers Total energy is the sum of the energies of the vehicles plus passengers Energy is transferred from vehicle to vehicle, and between passengers and vehicles. Energy is transferred from vehicle to vehicle, and between passengers and vehicles.

34 Fall from height Longer falls mean more kinetic energy Longer falls mean more kinetic energy Terminal velocity reached at about 60 ft. Terminal velocity reached at about 60 ft. Elastic surfaces will absorb some of the energy of the falling person Elastic surfaces will absorb some of the energy of the falling person Inelastic surfaces cause ALL of the energy of the fall to be absorbed by the body Inelastic surfaces cause ALL of the energy of the fall to be absorbed by the body

35 QUIZ! Lets see what stuck. Please your answers to:

36 Question 1 How many laws of motion did Isaac Newton posit? How many laws of motion did Isaac Newton posit?

37 Question 2 Which object has greater momentum? Which object has greater momentum? A speeding bullet A speeding bullet A fully loaded ambulance at 10 mph A fully loaded ambulance at 10 mph

38 Question 3 List a type of injury that could be caused by each of the following: List a type of injury that could be caused by each of the following: Compressional Force Compressional Force Torsional Force Torsional Force Frictional Force Frictional Force

39 Question 4 Which of the following is true regarding the magnitude of the forces involved in a vehicle collision? Which of the following is true regarding the magnitude of the forces involved in a vehicle collision? A. The mass of the vehicle is more important than the speed B. The mass of the vehicle is less important than the speed C. The area of collision matters the most D. Airbag deployment matters the most

40 Question 5 Which seatbelt will reduce the force of impact best? Which seatbelt will reduce the force of impact best? A. A seatbelt that does not flex B. A flexible seatbelt that stretches slightly C. No seatbelt

41 Question 6 What are the three causes of injury from explosions? What are the three causes of injury from explosions?

42 Question 7 How is it possible for electricity to cause burns? How is it possible for electricity to cause burns?

43 Question 8 What determines whether an injury will be blunt or penetrating? What determines whether an injury will be blunt or penetrating?

44 Question 9 Energy cannot be __________________ or ___________________, only ________________ or ______________. Energy cannot be __________________ or ___________________, only ________________ or ______________.

45 Question 10 Why are motor vehicle collisions so damaging to the human body? Why are motor vehicle collisions so damaging to the human body?

46 Please your answers to:


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