Biomechanics Flashcards
(18 cards)
Newtons 3 Laws
The law of inertia:a body at rest will remain at rest, and a moving body will continue to move at a constant speed in the same direction unless acted upon by an unbalanced force
Law of acceleration: force is directly proportional to mass and acceleration
Action-reaction:for every action there is an opposite and equal reaction
Momentum
Momentum refers to that once a body is moving the momentum of the body is a product of the mass and velocity
Impulse
Impulse is the change of momentum of a body over a given time
Levers
1st class: effort downwards, pivot, load downwards
2nd class: pivot, load downwards, effort upwards
3rd class: pivot effort upwards, load downwards
Torque
Defined as a force to cause rotation
Balance
The ability to maintain the line of gravity within the base of support
ROM
The flexibility of movement at a joint
Drag
The force which opposes the relative motion of an object through friction
Bernoulli’s principle
Increase in the speed of a liquid will decrease the pressure and a decrease in the speed of a liquid will increase the pressure
Magnus effect
Defined as the force that creates lift
Laminar flow
Turbulent flow
Laminar: fluid travels smoothly in regular paths
Turbulent: fluid undergoes irregular fluctuations and mixing
Form drag
Form drag: created by pressure difference between front and back of a moving object through liquid
Factors affecting form drag
-cross sectional area eg cyclist in a crouched vs upright position
-Velocity of the object, higher speed greater from drag
-shape of object, round ball vs oval ball
Surface drag
Friction produced between fluid and surface
Factors affecting surface drag
-velocity of object
-roughness of object, this is why athlete wear tight fitting clothes in skating, cycling etc
-surface area of object
Wave drag
Resistance formed by the creation of waves
Factors affecting form drag:
-velocity of the wave
-technique, more streamlined less wave drag, underwater less wave drag etc
-open water vs closed conditions
Coefficient of restitution
Measures elasticity of the collision between an object and a given surface
Factors affecting CoR
-equipment eg baseball bat can be wooden or aluminum
-condition of balls
-condition of playing surface
Angular momentum
Angular velocity is the speed of a rotating object
Moment of inertia is the resistance of a rotating object to change its state of motion
Angular momentum is angular velocity x moment of inertia
Angular momentum and Moment of inertia
If body’s mass is close to the axis of rotation its easier to manipulate
Moment of inertia would be smaller increasing angular velocity
Moving mass away from point of rotation decreases angular velocity
Boundary layer
Thin layer of air surrounding the ball
