Biomechanics Flashcards
Momentum
Is a measure of the amount of motion possessed by a moving body and can be expressed mathematically as P = M x V
Conservation of Momentum
Principle states the total momentum of two objects before and after impact are equal
Impulse
The application of force over a period of time to change the momentum of an object
Coefficient of Restitution
Measures the elasticity of a collision between an object and a given surface. It measures how much energy remains in the object after a collision takes place
Newtons Second Law
The rate of change of acceleration to a body is proportional to the force applied to it and inversely proportional to the mass of the object (law of acceleration)
Force = Mass x Acceleration
Newtons Third Law
For every action there is an equal and opposite reaction
Force
the action of one object to another, it is the product of mass times acceleration, represented mathematically as; F = M x A
Torque
The tuning effect created as a result of an eccentric force being applied around a pivot or axis
Torque = Force x Distance
Moment Arm
The distance between where the force is applied and the axis of rotation
Lever
a rigid object that is used with an axis to either multiply the mechanical force (effort) or resistance force (load) applied to it.
Angular Momentum
Angular momentum = angular velocity x moment of inertia
Angular Velocity
Refers to the velocity or speed of a rotating object
Moment of Inertia
Refers to the resistance of a rotating object to change its state of motion
Moment of Inertia = mass of the object x radius of rotation
Conservation of Angular Momentum
Means that a spinning body will continue spinning indefinitely unless an external force acts on it
Perpendicular Distance
the perpendicular distance between two objects is the distance from one to the other, measured along a line that is perpendicular to one or both
Fluid Resistance
the forces a fluid places on a moving object in the opposite direction to the movement, also known as drag
Form Drag
resistance created by pressure differential between front and back of an object moving through fluid
Wave Drag
resistance formed by creation of waves at the point where air and water interact
Surface Drag
friction produced between fluid and surface of a moving object
Boundary Layer
thin layer of air surrounding or ‘attached’ to the ball
Laminar Flow
a type of fluid flow in which moves smoothly in individual layers or streams
Turbulent Flow
flow in which the velocity at any point varies erratically
Buoyancy
refers to the upward force that keeps things afloat
Lift
refers to the component of force that acts perpendicular to the direction of flow, lift is created by different pressures (high/low) on opposite sides of an object due to fluid flow past the object
Bernoulli’s Principle
states that as the velocity of fluid increases, the pressure of the fluid exerts on an object decreases. Velocity is inversely proportional to pressure
Fluid
the natural science of fluids (liquids and gases) in motion
Drag
the component of dynamic fluid force that acts in opposition to the relative motion of the object with respect to the fluid
Pressure Differential
differential pressure is a pressure that is measured relative to the pressure in the atmosphere around it
Magnus Effect
describes the effect of rotation on an objects path as it movies through a fluid (it applies Bernoulli’s principle to explain the effect spin has on the trajectory or the flight path of an object)
Spin
when a ball is struck with an eccentric force (off centre), there is both linear and angular rotation (the rotating ball interacts with oncoming air)
Trajectory
the flight path of a projectile is called its trajectory
Eccentric Force
a force whose line of action does not pass through the centre of gravity of a body on which it acts
Magnus Force
describes the effect of rotation on an objects path as it moves through a fluid
Force-motion
When a body is acted upon by a constant force, its resulting acceleration is proportional to the force and inversely proportional to the mass (F = ma). Newton’s Second Law.
Force-time
When a force is applied to a ball its momentum changes, this is called impulse and is expressed as force x time (ft).
Inertia/Moment of Inertia
Inertia/moment of inertia – resistance to change in motion. Moment of inertia = resistance to rotational motion, the sum of mass and the radial distance from the axis of rotation. I = mr.
Range of Motion
The type of body movements used to produce a movement (movement around the joint).
Balance
The ability to neutralise forces that disturb equilibrium in order to maintain or hold its position.
Segmental Interaction/Coordination Continuum
Energy that is transferred across body segments and joints in a sequence of movements (kinetic chain).
Optimal Projection
When angle, velocity and height of release combine to meet the demands of the task.
Spin
The term used to describe the effect of rotation on an object’s path as it moves through a fluid.
