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)