4.3 Biomechanics Flashcards
Define Biomechanics
Biomechanics: application of mechanical principles (force & motion) related to the human body and sporting implements
What mathematical measures are used to measure biomechanics?
Scalers & Vectors
- scalar quantity - has only magnitude (size)
- vector quantity - has both magnitude and direction
Define the terms force, speed, velocity, displacement, acceleration, momentum and impulse.
3.1
force - push or pull upon an object resulting from the object’s interaction with another object
speed - the rate at which an object covers distance
velocity - change in displacement divided by the time taken for the change to take place
displacement - the difference between an object’s final position and it’s starting position
acceleration - the rate of change of velocity per unit of time
momentum - the quantity of motion of a moving body, measured as a product of its mass and velocity
impulse - change of momentum of an object when the object is acted upon by a force for an interval of time
Explain the relationship between distance and direction.
Distance does not depend on direction.
Displacement is the difference between an object’s final position and it’s starting position. Displacement does depend on direction.
How do speed and velocity differ?
speed: how fast you are travelling
velocity: how fast (speed) you are travelling in a given direction (vector quantity)
E.g.
Speed of 10m/s
Velocity of 10m/s east
What is the formula of velocity?
What is the formula of acceleration?
change in velocity: final velocity - initial velocity
change in time: finish time - start time
What are the formulas for: speed, direction & time?
Analyse velocity (speed)–time graphs of sporting actions.
3.2
Velocity-time graphs: illustrate how an object’s speed changes over time.
* The steeper the gradient of the line, the greater the acceleration.
* can look simialr to speed-time graphs, velocity-time graphs can have negative values + direction
What is the difference between a velocity–time graph and a speed-time graph?
3.2
- velocity graphs need a direction
- speed graphs have only positive values, velocity can also have negative values
What do ____ mean on velocity-time graphs?
- positive slopes
- horizontal lines
- negative sloped
- curved slope
3.2
- positive slopes: speed increasing/object accelerating
- horizontal lines: travelling at constant speed
- negative slopes: speed decreasing/negative acceleration
- curved slope: acceleration changing/non-uniform acceleration
Analyse distance–time graphs of sporting actions.
3.2
What do ____ mean on distance-time graphs?
- positive slopes
- horizontal lines
- negative sloped
- curved slope
3.2
Analyse force–time graphs of sporting actions.
3.2
Define the term centre of mass.
3.3
Centre of mass - mathematical point around which the mass of a body or object is evenly distributed
the lower the centre of mass of an object the more stable it is
How does the centre of mass change throughout movement?
3.3
What is the base of support?
What is the line of gravity?
3.3
What is the relationship between stability and the centre of mass (COM)?
3.3
Explain that a change in body position during sporting activities can change the position of the centre of mass.
3.4
Centre of mass does not always exist inside the body
* COM= axis for all free airborne rotations of the body or object, for example, somersaulting in diving
What are levers?
What are the different parts of levers?
3.5
levers are:
* simple machines that help us apply force.
* rigid structures, hinged at some part w/ forces applied at two other points
What are the functions of a lever?
3.5
- increase the load/force that can be moved with a given effort (e.g. crowbar)
- increase the velocity at which an object will move with a given force (e.g. golf club)
Distinguish between first, second and third class levers.
3.5
First class lever: The fulcrum lies btw. the effort and the load.
Second class lever: The load lies btw. the fulcrum and the point of effort.
Third class lever: The effort lies between the load and the fulcrum.
Explain how first class levers work.
3.5
First class lever: The fulcrum lies btw. the effort and the load.
* often used to magnify force
* The effort arm may be smaller than, equal to or bigger than the resistance arm. Fairly rae in human body
Whats an example of a first class level in the human body?
3.5
Explain how second class levers work.
3.5
Second class lever: The load lies between the fulcrum and the point of effort.
- The mechanical advantage is greater than in 1, and a small effort force can overcome a large resistance
- Very rare in the human body, except from calf muscles
Explain how second class levers work.
3.5
Second class lever: The load lies between the fulcrum and the point of effort.
- The mechanical advantage is greater than in 1, and a small effort force can overcome a large resistance
- Very rare in the human body, except from calf muscles
Explain how third class levers work.
3.5
Third class lever: The effort lies between the load and the fulcrum.
* often used to magnify speed or length of the lever arm
* Effort arm smaller than resistance arm.
* Mechanical advantage is less than 1, but greater angular velocity (advantage in range of motion and speed)
How to remember levers?
3.5
Whats an examples of first class levers within the human body and sporting situations
3.6
State one muscle-lever per class.
3.5
Whats an examples of second class levers within the human body and sporting situations
3.6
Whats an examples of third class levers within the human body and sporting situations
3.6
Describe the relationship between linear momentum and impulse in the context of Newton’s Second Law.
3.7
Apply Newton’s Law of Inertia to a sporting context
3.8
Apply Newton’s Law of Acceleration to a sporting context
3.8
Apply Newton’s Law of Action/Reaction to a sporting context
3.8
Whats a torque?
3.9
Explain the concept of angular momentum in relation to sporting activities.
3.10
Explain how a gymnast can alter the speed of rotation during flight. (7 marks)
3.10
Explain how shot-putters use the spin technique prior to the release of the shot ( 4 marks)
3.10
Define and explain projectile motion
3.11
Projectile motion motion of an object thrown or projected into the air, subject to only the acceleration of gravity.
Explain how gravity and air resistance impacts projecitle motion.
3.11
What are the factors that affect projectile motion at take-off or release.
3.11
- Angle of Release
- Speed of Release
- Height of Release
Explain how speed of release affects projectile motion at take-off or release.
3.11
Explain how the angle of release affects projectile motion at take-off or release.
3.11
Explain how the height of release affects projectile motion at take-off or release.
3.11
Discuss how the factors that affect projectile motion can influence shot put technique. (6)
3.11
What is Bernoulli’s principle?
3.12
Bernoulli’s Principle states that as fluid velocity increases, pressure decreases (the relationship between air flow velocity and air pressure is an inverse one)
What is the Magnus Effect?
3.12
Outline the Bernoulli principle with respect to projectile motion in sporting activities.
3.12
The relationship between air flow velocity and air pressure is an inverse one, and is expressed in Bernoulli’s principle. The pressure difference causes the spinning golf ball to experience a force directed from the region of high air pressure to the region of low air pressure. A golf ball with backspin will experience higher air pressure on the bottom of the ball and lower air pressure on the top of the ball, causing a lift force (from high air pressure to low air pressure).
When an object is moving through the air it is important to consider the relative air flow on different sides of the object. The airflow difference between opposite sides (eg bottom and top of a spinning golf ball) of the object moving through the air causes a pressure difference between the two sides. The lift force is perpendicular to the direction of the air flow.
