Biomechanics - Linear Motion & Levers Flashcards
What is Linear Motion?
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 the purpose of Newton’s Laws of Motions?
They describe the relationship between a body and the forces acting upon it, and the body’s motion in response to these forces to help us understand human movement.
What does Newton’s First Law of Motion state?
Law of Inertia
“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 Inertia?
The resistance an object has to a change in its state of motion.
What does Newton’s Second Law of Motion state?
Law of Acceleration
“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 occurs in the direction in which the force acts.”
What 2 things determine the acceleration a body experiences?
- The magnitude (size) of the force
- The direction in which the force acts
What does Newton’s Third Law of Motion state?
Law of Action/Reaction
“For every force that is exerted by one body on another, there is an equal and opposite force exerted by the second body on the first”
What is Ground Reaction Force?
The equal and opposite force exerted on a performer who applies a muscular force on the ground.
What is a Scalar Quantity?
A measurement described in terms of MAGNITUDE (size) only.
What is a Vector Quantity?
A measurement described in terms of both MAGNITUDE and DIRECTION.
What is Speed?
- The rate of change of position
- A body’s movement per unit of time
- Measured in m/s or m.s-1
What is Distance?
The length of the pat a body follows when moving from one position to another.
What are the 3 aspects of the SDT memory tool?
Distance = Speed x Time
Speed = Distance / Time
Time = Distance / Speed
What is the Centre of Mass?
- The point of concentration of mass
- The point of balance of the body
What is the Line of Gravity?
This is the line extending vertically downwards from the centre of mass
State two factors that affect the stability of a gymnast holding a headstand.
- Height of centre of mass of the gymnast
- Area of base of support for the headstand
- Position of line of gravity and body mass
- The mass of the body
What are the 3 components of a Lever?
- Fulcrum
- Resistance
- Effort / Force
In terms of Levers, what is the RESISTANCE?
The weight to be moved by the lever system
Identify the class of lever operating at the ankle
Second class lever system
What does a 3rd Class Lever look like?
Effort Resistance
____________^____________________________|
^
Fulcrum
What is the middle component of a 2nd Class Lever
Resistance
What is a 1st Class Lever?
The fulcrum lies between the effort and resistance
What is a 2nd Class Lever?
The resistance is between the fulcrum and effort
What is a 3rd Class Lever?
The effort is between the fulcrum and resistance
What is Mechanical Advantage?
Where the force arm is longer than the resistance arm.
What is Mechanical Disadvantage?
Where the resistance arm is longer than the force arm
What is the force arm?
- The length of the line between where the fulcrum and effort are labelled
OR
- The distance between the point where the effort acts and the fulcrum of the lever
What is the resistance arm?
- The length of the line between where the fulcrum and resistance are labelled
OR
- The distance between the point where the resistance acts and the fulcrum of the lever
State one mechanical advantage of the lever system operating at the ankle joint during a jump shot in basketball
- Overcomes heavy loads / weight
(Do not accept carry / withstand / support, must refer to lifting or moving)
- Large force is generated / longer effort arm / reduced effort needed
Define Mass
- The quantity of matter a body possesses
- Measured in Kg
Define Weight
- The gravitational force exerted on an object
- Measured in Newtons
Define Displacement
The length of a straight line between the starting and finishing position
Define Velocity
- Rate of change of displacement
- How fast a body travels in a given direction
- Displacement (m) / Time (s)
- Measured in m/s or m.s-1
Define Acceleration
- Rate of change of velocity of an object
- Change in Velocity (m/s) / Time (s)
- Measured in m/s/s or m.s-2
Define Momentum
- Amount of motion a body possesses
- The product of the mass and velocity of an object
- Momentum = Mass (kg) x Velocity (m.s-1)
- Measured in kgm/s or kgm.s-1
What is an external force?
Any force which comes from outside the body
What is an internal force?
A force generated by the skeletal muscles
Which Vertical Forces act on a sports performer / object?
- Weight (Gravity)
- Reaction Force
Which Horizontal Forces act on a sports performer / object?
- Friction (Frictional force)
Static Friction
Sliding Friction - Air resistance
What is Friction?
A force which occurs when two or more bodies are in contact with one another
What is Air Resistance?
A force that acts in the opposite direction to the motion of a body travelling through the air
What is Net Force?
- The resultant force acting on a body when all other forces have been considered
- Balanced forces v Unbalanced forces
What is Impulse?
- The time it takes for a force to be applied to an object or body
- Calculated as Impulse (Ns) = Force x Time
What impact does Impulse have on Momentum?
Increased impulse increases the rate of change of momentum, therefore causing a large change in velocity.
Describe the forces acting on a performer who is running.
A. Gravity B. Friction C. Air resistance D. Action force/muscular forces E. Reaction forces/ground reaction force
Name the lever system operating at the elbow during elbow extension
Third class / order lever
