Chapter 3 - Basic Biomechanical Factors & Concepts

Biomechanics

study of the mechanics as it relates to the functional and anatomical analysis of biological systems, especially in humans

Statics

body experience equilibrium; study of systems that are in a constant state of motion, whether at rest or with no motion or moving at constant velocity without acceleration.

Dynamics

unbalanced due to unequal forces acting on the body; study of systems in motion with acceleration

Kinematics

description of motion and includes consideration of time, displacement, velocity, acceleration, and space factors of a system's motion

Kinetics

study of forces associated with the motion of a body

Mechanical Advantage

Load Divided by Effort

Machine Function

1. Balance multiple forces

2. Enhance force

3. Enhance ROM & Speed of Movement

4. Alter resulting direction

Levers, wheels-axles, pulleys

3 types of machines found IN the body

Incline plane, Screw, Wedge

3 types of machines NOT found in the body

Bone

A lever can be represented by what body part?

Joints

An axis can be represented by what body part?

Muscle

The force (effort, E) can be represented by what body part?

Resistance

Load & Weight are AKAs for what?

Torque

moment of force; turning effect of an eccentric force

Force arm

perpendicular distance between location of force application and axis

Moment arm, force arm, torque arm

Force Arm AKAs

Scalar Quantities

described by magnitude (or numerical value) alone such as speed in mph or m/s

Vector Quantities

described by both magnitude and direction such as velocity in miles per hour in an eastward direction

Displacement

actual distance that the object has been displaced from its original point of reference

Distance

actual sum length of measurement traveled

angular displacement

change in location of a rotating body

linear displacement

distance that a system moves in a straight line

velocity

includes the direction and describes rate of displacement

law of inertia

A body in motion tends to remain in motion at the same speed in a straight line unless acted on by a force; a body at rest tends to remain at rest unless acted on by a force

inertia

resistance to action or change

acceleration

the rate of change in velocity; a change in the acceleration of a body occurs in the same direction as the force that caused it

law of reaction

For every action there is an equal and opposite (law) of _______

friction

force that results from the resistance between surfaces of 2 objects from moving upon one another

static friction

the amount of friction between two objects that have not yet begun to move

kinetic friction

friction occurring between two objects that are sliding upon one another

greater

static friction is always _____ than kinetic friction

balance

ability to control equilibrium, either static or dynamic

equilibrium

state of 0 acceleration where there is no change in the speed or direction of the body, there are 2 types: static and dynamic

stability

the resistance to a change in the body's acceleration or disturbance of the body's equilibrium

balance

_____ depends upon the direct proportion to the size of the base, weight, and height of center of gravity

muscle

The main source of force that produces or changes movement of a body segment

Mechanical loading

can cause fractured bones, dislocated joints, and disruption of muscles and connective tissue

momentum

equal to mass times velocity

walking

person throws the body in and out of balance with each step

running

inertia is high, the center of gravity has to be lowered to maintain balance when stopping or changing direction

jumping activities

the center of gravity needs to be raised as high as possible

mass

amount of matter in the body