Mechanics of Human Movement Exam 1

Biomechanics

the application of mechanical principles in the study of living organisms; examining the forces acting on (external) and within (internal) a body, and the effects of these forces

Mechanics

a branch of physics that analyzes the action of forces and particles of mechanical systems

Rigid body

a system of particles (i.e., a body) which does NOT deform

Rigid body mechanics

application of mechanical principles to a rigid body or system of rigid bodies

Elasticity

the propensity of a material to return to its original shape when deformed

Plasticity

propensity of a material to undergo permanent deformation when loaded

Viscoelasticity

material exhibits both viscous and elastic characteristics when deformed (i.e., dependent on loading rate)

Fluid mechanics

application of the principles of mechanics to fluids (liquid and/or gases)

Rectilinear

linear motion along a straight line (ex., running)

Curvilinear

linear motion along a curved line (ex., long jump)

Linear motion

motion along a line with all parts of the body moving the same distance in the same direction at the same time

Angular motion

all parts of the body move in a circle about a central line or point (axis of rotation)

Length

unit = meters (m)

Mass

unit = kilograms (kg)

Time

unit = seconds (s)

1 in

= 2.54 cm

1 mi

= 1.61 km

1 lb

= 4.45 N

Kilo

= 1000 =10^3

Centi

= 0.01 = 10^-2

Milli

= 0.001 = 10^-3

Axis of rotation

Imaginary axis the object is spinning about; perpendicular to the plane of motion.

Order of operation

PEMDAS.

Isolate x

Isolate x on one side of the equation.

Unit conversions

Perform unit conversions between common biomechanical units.

Common biomechanical units

Cm, m, km, ft, mile.

Trigonometry

Calculate unknown variables using trigonometry.

SOH-COA-TOA

Sin = SOH, Cos = COA, Tan = TOA.

Pythagorean theorem

A^2 + B^2 = C^2.

Kinematics

Descriptions of motion WITHOUT references to force causing the motion.

Linear kinematics

Is the kinematics of a particle, object, or system undergoing linear motion.

Vector

A quantity that has both direction and magnitude.

Linear displacement

Describes a change in linear position.

Distance

(scalar) Length of path.

Displacement

(vector) Difference between initial and final positions, independent of path 'as the crow flies'.

Speed

The rate at which a body moves from one position to another; scalar.

Velocity

The rate at which a body moves from one position to another; vector.

Linear velocity

Describes the ratio of change of linear or angular position with respect to time.

Linear acceleration

Rate of change of linear or angular velocity with respect to time.

Movement efficiency

The ratio of the magnitude of displacement to the distance traveled

Calculate movement efficiency

ME = displacement/distance = (unitless answer).

Acceleration

Rate of change of linear or angular velocity with respect to time.

Instantaneous velocity

Specifies how fast and in what direction one is moving at one particular point in time; the magnitude of instantaneous velocity is exactly the same as instantaneous speed.

Breaking

Magnitude and velocity decrease; object slows down or decelerates.

Propulsion

Magnitude and velocity increases; object speeds up or accelerates.

No acceleration

Constant velocity, ex, cruise control.