Download ESS 303 -- Biomechanics

ESS 303 – Biomechanics
Hydro- and Aerodynamics
Air & Water Resistance
 Drag force
 Opposite direction of movement through
medium
 Depends on coefficient of friction for the
surrounding medium
 Types of drag
 Skin friction (surface drag)
 Profile drag (based on an object/person’s shape)
 Wave drag (air-water interference – think of
splashing)
Skin Friction
Profile Drag
Wave Drag
Making Drag Work For You
Propulsive force in swimming
Flat hand in stroke
Tilted hand when treading water
Bernoulli’s Principle
Lift force
Pressure inversely proportional to
velocity
Lift
Magnus Effect
Low Velocity
(High Pressure)
Ball’s Motion
High Velocity
(Low Pressure)
Magnus Effect
Magnus Effect
Center of Buoyancy
 Different from center
of mass (COM) or
center of gravity
(CG)
 Effects body and
appendage position
when floating
CG
CB
Angle of Attack
Zero angle of attack, zero lift force,
minimum drag force
High angle of attack, small lift force,
large drag force
Small angle of attack, high lift force,
small drag force
Terminal Velocity
Force from the acceleration of gravity
countered by air-friction force
Acceleration
of Gravity
Air Friction
Terminal Velocity