Kinematics of Trauma

Question 1

Kinetic Energy

Answer 1

The energy possessed by a body because of its motion, equal to one half (1/2) the mass of the body times (x) the square of its speed.

Formula: KE = ( MV ² ) / 2

      • Where M = Mass (weight)
      • Where V = Velocity (speed)

Speed is more of a factor in determining force on a body than the mass of that body.

Examples:

— 180 lbs. at 30 mph = 81,000 KE units
— 150 lbs. at 40 mph = 120,000 KE units
— 180 lbs. at 40 mph = 144,000 KE units

Question 2

Newton’s 1st Law of Motion

(Inertia)

Answer 2

Newton’s 1st law states that if a body is at rest or moving at a constant speed in a straight line, it will remain at rest or keep moving in a straight line at constant speed unless it is acted upon by a force.

A body at rest will stay at rest, and a body in motion will stay in motion until a force acts upon it

Question 3

Newton’s 2nd Law of Motion

( F = ma )

Answer 3

Newton’s 2nd law describes the changes that a force can produce on the motion of a body.

It states that the time rate of change of the momentum of a body is equal in both magnitude and direction to the force imposed on it.

The momentum of a body is equal to the product of its mass and its velocity — momentum, like velocity, is a vector quantity, having both magnitude and direction.

For a body whose mass (m) is constant, it can be written in the form:

      • F = ma

Where F (force) and a (acceleration) are both vector quantities

If a body has a net force acting on it, it is accelerated in accordance with the equation.

Conversely, if a body is not accelerated, there is no net force acting on it.

Question 4

Newton’s 3rd Law of Motion

(Action and Reaction)

Answer 4

Newton’s 3rd law states that when two bodies interact, they apply forces to one another that are equal in magnitude and opposite in direction.

The third law is also known as the “law of action and reaction”.

For every action, there is an opposite and equal reaction

If there is no net force acting on a body, either because there are no forces at all or because all forces are precisely balanced by contrary forces, the body does not accelerate and may be said to be in equilibrium.

Conversely, a body that is observed not to be accelerated may be deduced to have no net force acting on it.

Question 5

Motor Vehicle Collisions

(MVC)

Answer 5

A Traffic Collision, also called a Motor Vehicle Collision (MVC), occurs when a vehicle collides with another vehicle, pedestrian, animal, road debris, or other moving or stationary obstruction, such as a tree, pole or building.

Types of Motor Vehicle Collisions:

— Frontal Impact / Stationary
— Lateral Impact / Side
— Rear End Impact
— Rotational Impact
— Rollover / Fall

Question 6

Frontal Impact

Answer 6

There are two main pathways a body will travel during a Frontal Impact:

— Up and Over
      • No seat belt present
      • Excessive breaking during collision
      • Star pattern mark on windshield

— Down and Under
      • Seat belt present

Common Up and Over Injuries:

— Head Injuries (Basilar Fractures)
— Spinal Injuries
— Chest Injuries
      • Great Vessel Injuries
      • Hemo / Pneumothorax
      • Fractures and Contusions
— Pelvic Fractures
— Abdominal Injuries
      • Solid and Hollow organs
      • Diaphragmatic Injuries

Common Down and Under Injuries:

— Pelvic and Hip Fractures
      • May cause injuries to abdominal organs
— Posterior Hip / Knee Dislocations
— Femur Fractures
— Fractures of the Lower Extremities