Stability is the ability of a body to resist being disturbed and to return to its original position. A stable body is hard to topple.

What is unstable equilibrium?

Unstable equilibrium is a state in which a slightly disturbed body moves further from its original position. A sprinter in the set position is an example.

What is neutral equilibrium?

Neutral equilibrium is a state in which a disturbed body stays in its new position. A ball rolling on a flat surface is an example.

How does the base of support affect stability?

A larger base of support increases stability. A wrestler widens their stance to be harder to move.

How does the height of the centre of mass affect stability?

A lower centre of mass increases stability. A defender bends the knees to lower the centre of mass.

WJEC A-Level Physical Education 601-8485-1

Performance Analysis and Fitness Testing

Topic overview The coaching process and approaches to performance analysis Video, notational and time-motion analysis Laboratory and field-based fitness testing Validity, reliability and interpreting test results

Levers and Movement Analysis

Topic overview The three orders of lever in the body Mechanical advantage and lever length Planes and axes of rotation Joint movement patterns in sporting actions

Joints and the Musculo-Skeletal System

Topic overview The skeleton, bone types and connective tissue Joint classification and types of synovial joint Major skeletal muscles and their actions Muscle fibre types, antagonistic action and contractions

Components of Fitness and Methods of Training

Topic overview Health-related and skill-related components of fitness Weight training, plyometrics and flexibility training Continuous, fartlek, interval and circuit training Altitude training and training in hot and cold climates Periodisation and SMART goal setting

Energy Systems and Principles of Training

Topic overview ATP and the ATP-PC system Anaerobic glycolysis and the aerobic system The energy continuum, thresholds and VO₂ max Applying the principles of training

Fatigue, Recovery and Rehabilitation

Topic overview Warm-up and cool-down Causes of fatigue, OBLA and DOMS EPOC and its alactic and lactacid components The fate of lactic acid and speeding up recovery Rehabilitation of minor injuries

Diet, Nutrition and Hydration

Topic overview A balanced diet and energy balance Carbohydrates, fats, proteins and the glycaemic index Diets for different sports and pre-competition meals Hydration and sports drinks

Personality

Topic overview Trait, social learning and interactionist theories Extroverts, introverts and Type A and Type B personalities Personality profiling and the profile of mood states

Stress, Arousal and Anxiety

Topic overview Stress, arousal and anxiety defined Drive, inverted-U and catastrophe theories The zone of optimal functioning and peak flow Measuring stress, arousal and anxiety Controlling stress, arousal and anxiety

Motivation and Self-Efficacy

Topic overview Intrinsic and extrinsic motivation Achievement motivation: need to achieve and need to avoid failure Competitiveness and developing achievement motivation in young performers Self-efficacy and its sources

Skill, Ability and Skill Classification

Topic overview Skill, ability, learning and performance Gross motor and psychomotor abilities Classifying skills on continua

Learning Curves, Theories and Stages

Topic overview Learning curves and plateaus Observational learning Reinforcement and drive reduction theory Fitts and Posner's stages of learning

Transfer, Practice, Guidance and Feedback

Topic overview Types of transfer Methods of practice Methods of guidance Types and uses of feedback

Sport, Culture and Society

Topic overview Culture, society and social institutions Sport as social control and socialisation Sport, national identity and government

The Emergence of Modern Sport

Topic overview Public schools and the three stages of athleticism Universities, codification and the spread of games From amateurism to professionalism and commercialisation Olympism, shamateurism and sport as a political tool

Social Differentiation in Sport

Topic overview Social stratification and class in sport Prejudice, stereotyping and discrimination Barriers to participation for disadvantaged groups Strategies to widen participation

Short-Term Responses to Exercise

Topic overview The heart as a dual-action pump and its control Cardiac dynamics, the cardiac cycle and the cardiac response Blood vessels, blood pressure and the vascular shunt Respiratory response to exercise intensity Neuromuscular responses, steady state and VO₂max

Long-Term Adaptations to Exercise

Topic overview Musculo-skeletal adaptations to training Cardio-respiratory adaptations to training Interpreting data on long-term adaptations

Carbohydrate Loading and Supplements

Topic overview Glycogen loading: depletion, repletion and tapering Protein supplements: whey and casein Creatine, caffeine and the misuse of supplements

Biomechanical Principles

Topic overview Newton's laws of motion in sport Momentum, impact and impulse Stability, equilibrium and friction

Linear and Angular Motion

Topic overview Distance, displacement, speed and velocity Acceleration and graphs of motion Angular displacement, velocity and acceleration Moment of inertia and conservation of angular momentum

Projectile Motion and Fluid Mechanics

Topic overview Factors affecting the flight of a projectile Lift forces and the Bernoulli principle Spin and the Magnus effect Drag, streamlining and laminar flow

Attitudes

Topic overview Attitudes, prejudice and stereotyping The triadic model of attitudes Changing attitudes through cognitive dissonance and persuasion

Aggression

Topic overview Aggression, assertion and types of aggression Theories of aggression Causes and control of aggression

Social Facilitation

Topic overview Audiences, co-actors and performance Theories of social facilitation Home field advantage and reducing social inhibition

Group Dynamics and Leadership

Topic overview The 6 Is and the formation of groups Task and social cohesion Group productivity, social loafing and the Ringelmann effect Leadership theories and styles Chelladurai's multi-dimensional model and the Leadership Scale for Sports

Attribution Theory

Topic overview Weiner's model of attribution Errors in attribution Learned helplessness and attribution retraining

Information Processing and Memory

Topic overview Welford's and Whiting's information processing models Memory stores and selective attention Strategies for improving memory Reaction time, response time and Hick's law The psychological refractory period, anticipation and motor programmes

Ethics, Deviance and Doping

Topic overview Fair play, sportsmanship and gamesmanship Deviance, Coakley's sports ethic and violence Reasons for doping and its ethics WADA, drug testing and biological passports

Sport and the Mass Media

Topic overview Functions and forms of the media in sport The symbiotic relationship and the golden triangle Media stereotypes and the dramatisation of sport

Commercialisation and Globalisation

Topic overview Sport as a commodity and consumerism Sponsorship, marketing and the sporting goods market Americanisation and globalisation theory Globalisation, financial gain and global migration

Mass Participation and Excellence

Topic overview Mass participation versus excellence Participation, lifestyle and movement between levels Talent identification and the elite pathway Sport organisations and recreational pathways

Biomechanical Principles

Stability, equilibrium and friction

3 things to know
A2 Unit 3

Overview

Stability and stable, unstable and neutral equilibrium, the base of support and centre of mass, the sprinter's set position, the coefficient of friction and its factors, sports shoes and low-friction sports.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Evaluation

How do sports shoes raise friction, and when is low friction an advantage?

Key term

What is stability?

Key term

What is stable equilibrium?

Questions from this subtopic

Each one with the model answer underneath.

1
What is stability?
Model answer
Stability is the ability of a body to resist being disturbed and to return to its original position. A stable body is hard to topple.
2
What is stable equilibrium?
Model answer
Stable equilibrium is a state in which a slightly disturbed body returns to its original position. A wide, low stance is an example.
3
What is unstable equilibrium?
Model answer
Unstable equilibrium is a state in which a slightly disturbed body moves further from its original position. A sprinter in the set position is an example.
4
What is neutral equilibrium?
Model answer
Neutral equilibrium is a state in which a disturbed body stays in its new position. A ball rolling on a flat surface is an example.
5
How does the base of support affect stability?
Model answer
A larger base of support increases stability. A wrestler widens their stance to be harder to move.
6
How does the height of the centre of mass affect stability?
Model answer
A lower centre of mass increases stability. A defender bends the knees to lower the centre of mass.

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Performance Analysis and Fitness Testing

Levers and Movement Analysis

Joints and the Musculo-Skeletal System

Components of Fitness and Methods of Training

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