Introduction. KIN335 Biomechanics Spring 2005

Transcription

1 Introduction KIN335 Biomechanics Spring 2005

2 What is Biomechanics? Bio- : Something to do with living or biological system -mechanics : Something to do with the analysis of forces and their effects Biomechanics: the study of forces and their effects on living system or application of mechanical principles to the study of living systems Herbert Hatze (1974) s definition Biomechanics is the study of the structure and function of biological systems by the means of the methods of mechanics

3 Why study biomechanics? Understand well why some sports techniques work and some don t Evaluate techniques better

4 Why study biomechanics? For athletic trainers, physical therapist, and peoples of sports medicine L4 L4 L5 L5 Diagnose the causes of an injury Provide the mechanical basis for taping techniques, braces, and other orthotic device Guide therapists in their prescriptions for rehabilitation (good vs. bad exercise) Spondylosis, Spondylolisthesis

5 What are the goals of exercise and sport biomechanics? Performance improvement Training improvement Injury Prevention & Rehabilitation Techniques to reduce injury Equipment design to reduce injuries

6 Bio- Overview Muscle Mechanics Filament theory Tissue Mechanics Stress, Strain, and their relationship

7 -mechanics Overview Mechanics : the science concerned with the effects of forces and acting on objects Rigid-body: Object is assumed to be perfectly rigid. No compliance to forces Rigid-body mechanics Applying Newton s laws

8 Newton s Laws 1 st Law of Motion: Conservation of Momentum Ever body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it. 2 nd Law of Motion: ΣF=ma The change of motion of an object is proportional to the force impressed and is made in the direction of the straight line in which the force is impressed. 3 rd Law of Motion: Action & Reaction To every action there is always opposed an equal reaction.

9 -mechanics Overview Rigid-body Mechanics Statics Dynamics Kinematics Kinetics Linear Angular Linear Angular

10 Basic Dimensions L M T Dimeinsion? : unit need to describe movement L = M = T = SI English m, km, cm in, ft, mile kg, g slug sec, min, hr sec, min, hr Secondary Units : N, lb (force); J, cal (energy), Pa (pressure),.

11 Length To describe how far. 1 m = ft 1 ft = m 1 m = 100 cm 1 km = 1000 m 1 in = cm 1 cm = inches 1 ft = 12 inches 1 mile = ft 1 mile = km 1 yard = 3 ft = m YK s height is 178 cm. What is his height in English unit (ft & in)? Marathon in Olympics is 26.2 miles. What is this length (km) in SI unit?

12 Prefix Multiples atto a Quintillionth femto f Quadrillionth pico p Trillionth tera T Trillion nano n Billionth 10-9 giga G Billion 10 9 micro µ Millionth 10-6 mega M Million 10 6 milli m Thousandth 10-3 kilo k Thousand 10 3 centi c Hundredth 10-2 hecto h Hundred 10 2 deci d Tenth 10-1 deca da Ten 10 1

13 Mass To describe how heavy The measure of inertia Inertia? The property of an object to resist changes in its motion 1 kg = slugs 1 kg = 1000 g cf) 1lb? 1 lb = kgf 1 kgf = lb 1 lb = 16 ounces YK s mass is 78 kg in SI unit. What is his weight in lb? Try to convert your weight (lb) into SI unit (kg).

14 Time To describe how long does it take 1 second 1 min = 60 sec 1 hr = 60 minutes = 3600 seconds If it took total 3953 seconds for a person to run given distance, convert time consumed into hour and minute bases.