Sports Training: Biomechanical Movement Flashcards
What is linear motion in the body?
Motion in a straight or curved line with all body parts moving the same distance at the same speed in the same direction
What is Newton’s first law?
The law of inertia
What is inertia?
The resistance an object has to a change in its state of motion.
What happens to inertia when the mass is large?
The bigger the mass, the larger the inertia of the body or object
What would be needed to change the inertia of an object or body that has a large mass?
More force will be needed to change its state of motion
What actions can occur when force changes the state of motion?
Starting
Stopping
Accelerating
Decelerating
Change direction
What does Newton’s first law state?
‘Every body continues in its state of rest or motion in a straight line, unless compelled to change that state by external forces exerted upon it’
What is Newton’s second law?
The law of acceleration
What does Newton’s second law (the law of acceleration) mean?
It means that the magnitude and direction applied to a body/object determine the magnitude and direction of the acceleration given to the body/object
What is the rate of acceleration directionally proportional to?
It is directly proportional to the force causing the change
What formula is used calculate the size of the force?
Force = mass x acceleration
What is mass measured in?
Kilogram (kg)
What is acceleration measured in?
Metres per second (m/s)
What does Newton’s second law state?
‘The rate of momentum of a body (or the acceleration for a body of constant mass) is proportional to the force causing it and the change that takes place in the direction in which the force acts’
How can acceleration be provided at the start of a sprint race?
An athlete will have to apply a large force internally with their gluteals, quadriceps and gastrocnemius as they drive forward
What is Newton’s third law?
The law of action/reaction
What does Newton’s third law state?
‘To every action [force], there is an equal and opposite reaction [force]’
What are the characteristics of action and reaction?
They are equal and opposite. They always occur in pairs
How is Newton’s third law demonstrated at a sprint start?
The athlete pushes back on the blocks as hard as possible (action) and the block pushes forward on the athlete (reaction). This provides forward acceleration on the athlete
What is ground reaction force (GRF)?
Force exerted on the ground by the body in contact with it
What happens when an individual is standing still on the ground?
The ground exerts a contact force (weight of the individual) and at the same time, an equal and opposite reaction force is exerted by the ground on the individual.
What is a scalar quantity?
When measurements are described in terms of their size or magnitude
What are examples of scalar quantities?
Speed, distance, mass and temperature
What is speed defined as?
As the rate of change of position
How do you calculate speed?
S=d/t
What is distance defined as?
Length of the path a body follows when moving from one position to another
What is the centre of mass?
The point of concentration of mass
The point of balance of a body
Where is the centre of mass for someone standing?
Between hip regions
What factors affect stability?
. The height of the centre of mass
. Position of the line of gravity
. Area of the support base
. Mass of the performer
What happens when you lower the centre of mass?
It will increase stability
Where should the position of the line of gravity be to increase stability?
Should be central over the base of support to increase it
How do you increase stability with the area of the support base?
The more contact points there are the larger the base of support becomes and therefore the more stable they become. Ex - more contact points on a headstand than a handstand
How do you increase stability through mass of the performer?
The greater the mass, the more stability there is because of increased inertia
What are the three main components of levers?
Fulcrum, resistance, and effort
What is the fulcrum?
A pivot
What is the resistance?
A weight to be moved
What is the effort?
Source of energy
What are the three types of levers?
1st, 2nd and 3rd class levers
What acts as the levers?
Bones
What acts as the fulcrum?
Joints
What provides the effort?
Muscles
What acts as the resistance?
Weight of body part
Where are each components placed on a first class lever?
The fulcrum is in the middle of effort and the resistance
Describe what a first class lever looks like
The fulcrum is in the middle of the lever arm. It is under the lever arm. Effort and resistance are above the lever and as arrows they are pointing down
Give an example of a first class lever.
Extension of the elbow
Movement of head during flexion and extension
Where are each components placed on a second class lever?
Resistance lies between fulcrum and effort
Describe what a second class lever looks like
Fulcrum placed under lever arm at one end. Effort placed above lever arm and on the other end with arrow pointing up. Resistance is above lever arm and in the middle with arrows pointing down
Give an example of a second class lever
Plantar flexion of the ankle
Where are each components placed on a third class lever?
Effort in middle of the fulcrum and resistance
Describe what a third class lever looks like.
Fulcrum under lever arm on one end. Resistance above lever arm on the other end with arrows pointing down. Effort above lever arm in the middle with arrows pointing up
Give an example of a third class lever
Hip flexion
Knee flexion
Elbow flexion
What does mechanical advantage and disadvantage depend on?
Length of the force arm and resistance arm
What is the effort arm?
Shortest perpendicular distance between fulcrum and effort
What is the resistance arm?
The shortest perpendicular distance between the fulcrum and the resistance
What is mechanical disadvantage?
When the resistance arm is greater than the force arm
What would be the result of mechanical disadvantage?
Lever system can not lift as heavy a load but can do it faster. It will also have a large range of movement
What is mechanical advantage?
When the force arm is longer than the resistance arm
What would be the result of mechanical advantage?
The lever system can move a large load over a short distance and requires little force. However it has a small range of movement and difficult to generate speed and distance
What is the mechanical advantage in second class levers?
Can generate much larger forces as it has to lift the whole body weight
What is the mechanical disadvantage in second class levers?
It is slow with limited range of movement
What is the mechanical advantage in first and third class levers?
Large range of movement and any resistance can be moved quickly
What is the mechanical disadvantage in first and third class levers?
Cannot apply much force to move an object
What is speed?
Speed is a scalar quantity and is defined as ‘the rate of change of a position’
How is speed calculated?
Speed (m/s) = distance covered in metres (m) / time taken in seconds (s)
What is velocity?
Velocity is a vector quantity and refers to how fast a body travels in a certain direction. It is ‘the rate of change of displacement’
How is velocity calculated?
Velocity (m/s) = displacement (m) / time (s)
On a distance time graph, the line remains straight the entire way through. What is happening?
The line does not go up or down. This means no distance has travelled because the performer is stationary
On a distance time graph, the line goes straight up at an angle. What is happening?
The direction of the line is constantly diagonal. This means the distance travelled is changing at a constant rate and at the same speed
On a distance time graph, the line gradually curves up. What is happening?
The curve gradually gets steeper. More distance is covered in a certain amount of time. The performer is accelerating
In a distance time graph, the line gradually slows after increasing. What is happening?
The curve levels off and so less distance is covered in a certain amount of time. The performer is decelerating
In a velocity time graph, the line remains the same the entire way through. What is happening?
The gradient remains constant which indicates the performer is travelling a constant velocity
In a velocity time graph, the line goes straight up at an angle what is happening?
The gradient gets steeper (increases) which indicates that the performer is moving with increasing velocity (accelerating)
In a velocity time graph, the line goes straight down at an angle. What is happening?
The gradient is decreasing indicating the performer has a decreasing velocity (deceleration)
In a velocity time graph, the line curves up and down below the x axis. What is happening?
As the curve goes below the x axis, this means there has been a change in direction
What is acceleration?
‘The rate of change of velocity’. It is measured in m/s*-2
What happens when velocity increases?
Positive acceleration occurs
What happens when velocity decreases?
Negative acceleration occurs
How do you calculate acceleration?
Acceleration (m/s/s) = change in velocity / time
What is momentum?
‘The product of mass and velocity of an object’. Momentum is a vector quantity
How do you calculate momentum?
Momentum (kgm/s) = mass (kg) x velocity (m/s)
What happens to momentum if mass or velocity increases?
Momentum also increases
How can momentum be conserved?
Occurs when a performer or object is in flight. When in flight neither mass or velocity can be altered
What is a vector quantity?
A quantity with a magnitude and direction
What are examples of vector quantitates?
. Displacement
. Velocity
. Momentum
What forces act on a performer during linear motion?
Internal and external
Vertical and horizontal
What is internal force?
Force generated by the skeletal muscle
What is external force?
Force that comes from outside the body
Examples of vertical force?
Gravity/weight and reaction
Examples of horizontal force?
Friction and air resistance
What is weight force?
Is the gravitational force that the Earth exerts on a body, pulling it down
What happens to weight when mass is greater?
The greater the weight force pulling down
What is reaction force?
Whatever the force acting on a performer during linear motion, a reaction force will be generated (Newton’s 3rd Law)
What is ground reaction force?
When an action force is applied to the ground and the ground applies an equal and opposite reaction force (Newton’s 3rd Law)
Examples of Horizontal forces?
Friction and air resistance
What is friction?
It is the opposite motion and occurs when two bodies are in contact
What are the two types of friction?
Static and sliding friction
What is static friction?
Force exerted when there is no motion between two surfaces
What is sliding friction?
When 2 bodies in contact have a tendency to slip/slide over
What is friction affected by?
- Roughness of the surface
- Mass of an object
- Temperature of the 2 surfaces
What is air resistance?
A force that acts in the opposite direction to the motion of a body travelling through the air
What is air resistance dependent on?
- Velocity of the moving body
- Frontal cross sectional area of the moving body
- The shape and surface characteristic of the moving body
How are free body diagrams shown?
Shown using arrows
How is weight shown on a free body diagram?
A force drawn down from the centre of mass
How is reaction shown on a free body diagram?
a force that starts from where 2 bodies are in contact. This can be foot with the ground
How is friction shown on a free body diagram?
A force that starts from where the 2 bodies are in contact and is opposite to the direction of any potential slipping. It is drawn in the same direction as motion
How is air resistance shown on a free body diagram?
A force drawn from the centre of mass opposing the direction of motion of the body
What is net force?
This is the resultant force activity on a body when all other forces have been considered.
What is a balanced force?
When there are 2 or more forces acting on a body that are equal in size but opposite in direction
When is the net force 0?
When there is no change in state of motion
What is an unbalanced force?
An unbalanced force is created when a force acting in one direction is larger than the force acting in the opposite direction.
What is upward acceleration?
When the reaction force becomes greater than the weight force
What is angular motion?
Refers to rotation and movement around a fixed point
When does angular motion occur?
When a force is applied outside the centre of mass
What are the axis of rotation?
. Transverse
. Sagittal
. Longitudinal
What is a transverse axis?
It runs from side to side across the body (somersault)
What is a sagittal axis?
It runs from front to back (cartwheel)
What is a longitudinal axis?
It runs from top to bottom (spinning in ice skating)
What is torque?
It is the turning force and is the reason angular motion occurs. Torque causes an object to turn about its axis of rotation
What 2 things is torque dependent on?
1) the greater the size of the force, the greater the torque
2) application of the same force further away from the axis will increase torque
How do you calculate moment of force/torque (Nm)?
Force (N) x perpendicular distance from the fulcrum (m)
How do you calculate the resistance arm?
Moment of force (Nm) = force (N) x perpendicular distance from fulcrum (m)
How does Newton’s first law apply to angular motion?
Every body continues in its state of rest or will turn about its axis of rotation unless compelled to change that state by an external force acting upon it
How does Newton’s second law apply to angular motion?
The rate of change of angular momentum (acceleration) a body is proportional to the force (torque) causing it and the change that takes place in the direction which the force (torque) acts
How does Newton’s third law apply to angular motion?
When a force (torque) is applied by one body to another, the second body will exert an equal and opposite force (torque) on the other body.
What is angular velocity?
Refers to rotational speed of an object and the axis about which the object is rotating. Its a vector quantity
How is angular velocity calculated (rad/s)?
Angular velocity (rad/s) = angular displacement (rad) / time taken (s)
What is angular acceleration?
Is the rate of change of angular velocity calculated by dividing the change in angular velocity (rad/s) by time taken (s)
How is angular acceleration (rad/s*2) calculated?
Angular acceleration (rad/s*2) = change in angular velocity (rad/s) / time taken (s)
What is moment of inertia?
Is the resistance of a body to change its state of motion when rotating
What is moment of inertia acting on a lever dependent on?
1) mass of the object
2) how mass is distributed from the point of rotation
How is moment of inertia affected by mass of the object?
The greater the mass, the greater the resistance to change and therefore the greater the moment of inertia
How is moment of inertia affected by distribution of mass from axis of rotation?
The closer the mass to the axis of rotation, the smaller the inertia. Thus, the easier it is to rotate . Increasing the distance of the distribution of mass from the axis of rotation will increase moment of inertia, but make rotation slower
What is angular momentum equal to?
Angular velocity x moment of inertia
What is conservation of angular momentum?
When a body will keep on spinning or rotating unless forces act upon it.
What happens when mass moves closer to the axis of rotation?
The moment of inertia decreases and angular velocity increases because angular momentum is conserved
What happens when mass moves away from the axis of rotation?
The moment of inertia increases and angular velocity decreases because angular momentum is conserved
What is projectile motion?
Refers to movement of either an object or the human body as it travels through the air
What factors affect the horizontal displacement of a projectile?
. Angle of release
. Velocity of release
. Height of release
What is the angle of release dependent on?
Dependent on height of release and landing
What is the angle of release when release height and landing is the same?
45 degrees
What is the angle of release when release height is greater than landing height?
Less than 45 degrees
What is the angle of release when release height is below landing height?
Greater than 45 degrees
What is fluid mechanics?
The study of an object or human body that travels through liquid or gas
What is dynamic fluid force?
Concerned with the movement of liquids and gases
Effects of dynamic fluid force?
Drag and lift
What is drag?
. Slows something down
. Resistance form
. Caused by a body travelling through a liquid
. Acts in opposition to direction of motion
. Has a negative effect on velocity
What are the two types of drag?
Surface drag and form drag
What is surface drag?
Friction between surface of an object and the fluid environment
How do swimmers reduce surface drag?
Swimmers wear specialised smooth suits, caps and shave off body hair. This makes them smooth and squash fleshy areas so as to become more streamlined. This reduces surface drag and increases velocity
What is form drag?
Relates to the impact of the fluid environment on an object. Forces affecting the leading edge of an object increases form drag. Forces affecting the trailing edge of an object reduces form drag
How do cyclists reduce form drag?
Cyclists get behind the first rider. Air passes around first rider and so form drag is reduced for second rider and they will require less energy
What is streamlining?
. Shaping a body so it can move through fluid effectively and quickly
. Streamlined bodies incorporate a ‘gradual taper’
. The streamlined shape allows air to move past in layers
. Enables air to flow smoothly
. Reduces fluid drag
What is turbulent flow?
Flow in which the fluid undergoes irregular fluctuations, or mixing, constantly undergoing changes in magnitude and direction. It increases friction and fluid drag and decreases velocity
What is laminar flow?
Layers of fluid flow and slide smoothly over one another. They undertake smooth paths, or layers. Less resistant to movement
What factors increase or reduce drag?
. Velocity of moving body
. Cross - sectional area of moving body
. Shape/surface of moving body
What is the effect of the velocity on the moving body?
The greater the velocity of a body through a fluid, the greater the drag force
In sports that are very quick, it is important to reduce the effects of drag
This is done by streamlining as much as possible
Describe 4 ways cyclists reduce drag?
Helmet -> designed to encourage laminar flow
Bike -> lightweight carbon fibre frame, aerodynamic features
Body position -> head over bars, low over front wheel, arms tucked
Clothing -> compressed clothing
What is the effect of the cross sectional area of the moving body?
The cross sectional area of a moving body can reduce or increase drag
A large cross sectional area will increase drag
In some sports reducing effects of drag is essential for success
Describe 2 ways a skier can reduce their cross sectional area?
. Position: reducing cross sectional area by crouching low
. Position: reducing cross sectional area by tucking arms in
What are the effects of the shale and surface characteristics of the moving body?
A more streamlined, aerodynamic shape reduces drag
Sports scientists are regularly trailing drag-resistant clothing
This helps competitors with ‘marginal gains’
