How can a performer's centre of mass lie outside the body?

A curved shape, such as a pike or an arched back, can leave the centre of mass outside the body.

Why does the Fosbury flop let a high jumper clear a higher bar?

The jumper arches over the bar so the centre of mass can pass just beneath it. Each body part clears the bar in turn, so less lift is needed.

Why do males often have a higher centre of mass than females?

Males tend to carry more of their mass in the upper body, around the shoulders. Females tend to carry more mass around the hips, lowering the centre of mass.

OCR A-Level Physical Education H555

Skeletal and Muscular Systems

Topic overview Shoulder, elbow and wrist joints and muscles Hip, knee and ankle joints and muscles Planes of movement, muscle roles and contractions Analysing movement in sporting actions Motor units and muscle fibre types

The Cardiovascular System

Topic overview Heart rate, stroke volume and cardiac output at rest The cardiac cycle and conduction system Cardiac responses to exercise and recovery The vascular shunt mechanism Venous return and heart rate regulation

The Respiratory System

Topic overview Breathing frequency, tidal volume and minute ventilation Mechanics of breathing at rest and in exercise Regulation of breathing Gas exchange at the alveoli and the muscles

Energy for Exercise

Topic overview ATP and coupled reactions The ATP-PC system The glycolytic system The aerobic system The energy continuum and intermittent exercise EPOC and the recovery process

Environmental Effects on Body Systems

Topic overview Altitude and oxygen delivery Acclimatisation and timing arrival at altitude Exercise in the heat and cardiovascular drift

Diet, Nutrition and Ergogenic Aids

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Aerobic Training

Topic overview VO₂max and the factors that affect it Testing aerobic capacity Continuous training, HIIT and target heart rates Adaptations to aerobic training

Strength and Flexibility Training

Topic overview Types of strength and strength testing Strength training methods Adaptations to strength training Types of flexibility and flexibility testing Flexibility training methods and adaptations

Periodisation of Training

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Training and Lifestyle Diseases

Topic overview Atherosclerosis and coronary heart disease Heart attack and stroke Asthma and COPD

Injury Prevention and Rehabilitation

Topic overview Acute and chronic injuries Risk factors, warm-up and cool-down SALTAPS, PRICE and concussion Fractures, joint injuries and muscle damage Treatments for sporting injuries

Biomechanical Principles and Levers

Topic overview Newton's laws and force calculations Forces and free body diagrams Centre of mass and stability Levers and mechanical advantage Limb kinematics, force plates and wind tunnels

Linear and Angular Motion

Topic overview Linear motion, distance and displacement Speed, velocity and acceleration Graphs of linear motion Angular motion and the axes of rotation Moment of inertia and conservation of angular momentum

Fluid Mechanics and Projectile Motion

Topic overview Air resistance and drag Factors affecting projectile distance Forces on a projectile and flight paths Bernoulli's principle and lift Spin and the Magnus effect

Skill Classification, Practice and Transfer

Topic overview Classifying skills by difficulty, environment and pacing Classifying skills by muscular involvement, continuity and organisation Whole, part, whole-part-whole and progressive part practice Massed, distributed, fixed and varied practice Transfer of learning between skills

Theories and Stages of Learning

Topic overview Operant conditioning Cognitive theory and insight learning Bandura's observational learning Fitts and Posner's stages of learning

Guidance and Feedback

Topic overview Verbal and visual guidance Manual and mechanical guidance Intrinsic, extrinsic, positive and negative feedback Knowledge of performance and knowledge of results

Memory Models

Topic overview Atkinson and Shiffrin's multi-store model Selective attention Craik and Lockhart's levels of processing

Personality and Attitudes

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Motivation and Arousal

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Anxiety

Topic overview State and trait anxiety Somatic and cognitive anxiety The zone of optimal functioning

Aggression

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Social Facilitation and Group Dynamics

Topic overview Social facilitation and inhibition Evaluation apprehension and reducing social inhibition Groups and Tuckman's stages of development Steiner's model, the Ringelmann effect and social loafing

Goal Setting

Topic overview Outcome, performance and process goals How goal setting improves performance The SMART principle

Attribution

Topic overview Weiner's model: locus of causality and stability Controllability, self-serving bias and attribution retraining Learned helplessness and mastery orientation

Confidence and Self-Efficacy

Topic overview Sports confidence, self-efficacy and self-esteem Vealey's model of sports confidence Bandura's four sources of self-efficacy Building confidence in performers

Leadership

Topic overview Effective, emergent and prescribed leaders Autocratic, democratic and laissez-faire styles Trait, social learning and interactionist theories of leadership Chelladurai's multi-dimensional model

Stress Management

Topic overview Stress and stressors in sport Self-talk, thought stopping and rational thinking Mental rehearsal, imagery, goal setting and mindfulness Relaxation, biofeedback, centring and breathing control

Sport in Pre-Industrial and Industrial Britain

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Sport in the 20th and 21st Centuries

Topic overview Amateurism and professionalism in the 20th century Social change and sport in 20th-century Britain Class, gender and access in 21st-century sport The globalisation of sport

The Olympic Games and Global Sporting Events

Topic overview Coubertin and the aims of the modern Olympics Berlin 1936 and Mexico City 1968 Munich 1972 and the Cold War boycotts Hosting a global sporting event

Drugs in Sport

Topic overview Legal supplements and illegal doping Why elite performers dope Consequences of doping for society, sport and performers Strategies against doping

Violence and Gambling in Sport

Topic overview Causes of player and spectator violence Implications of violence in sport Preventing violence among players and spectators Match fixing, bribery and illegal betting

Commercialisation and the Media

Topic overview What drives the commercialisation of sport Impacts of commercialisation Television, radio, press and internet coverage Positive and negative effects of the media Sport as a commodity and the golden triangle

Routes to Sporting Excellence

Topic overview From talent identification to elite performance Schools, clubs and universities in elite success UK Sport and the national institutes Drop-out from elite programmes

Modern Technology in Sport

Topic overview Technology and elite performance Technology and general participation Technology and fair outcomes Technology and entertainment

Biomechanical Principles and Levers

Centre of mass and stability

3 things to know
Component 01

Overview

Centre of mass and how it moves, the Fosbury flop, sex differences, stability and the height of the centre of mass, the base of support, line of gravity and body mass, the sprint set position and the goalkeeper's ready position.

What you need to know

Answer each one before you reveal it.

Your recallNot started

Key term

Define centre of mass.

Key term

Why does a performer's centre of mass move during a movement?

Key term

What happens to a gymnast's centre of mass when both arms are raised above the head?

Questions from this subtopic

Each one with the model answer underneath.

1
Define centre of mass.
Model answer
The centre of mass is the point at which a body is balanced in all directions. The centre of mass is the point from which weight appears to act.
2
Why does a performer's centre of mass move during a movement?
Model answer
The centre of mass depends on how body mass is arranged. A limb moved away from the trunk shifts the centre of mass towards it.
3
What happens to a gymnast's centre of mass when both arms are raised above the head?
Model answer
The centre of mass moves upwards towards the head. A higher centre of mass makes the gymnast less stable.
4
How can a performer's centre of mass lie outside the body?
Model answer
A curved shape, such as a pike or an arched back, can leave the centre of mass outside the body.
5
Why does the Fosbury flop let a high jumper clear a higher bar?
Model answer
The jumper arches over the bar so the centre of mass can pass just beneath it. Each body part clears the bar in turn, so less lift is needed.
6
Why do males often have a higher centre of mass than females?
Model answer
Males tend to carry more of their mass in the upper body, around the shoulders. Females tend to carry more mass around the hips, lowering the centre of mass.

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Skeletal and Muscular Systems

The Cardiovascular System

The Respiratory System

Energy for Exercise

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ADoping can damage health and add to healthcare costs.

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