biomechanics Flashcards
define general motion
a combination of both linear and angular motion. the most common form of motion in sporting activities.
define linear motion
where movement is along a straight or curvilinear path, there is no rotation and all body parts move in the same direction at the same speed.
define angular motion
where all parts of a body move through a rotational pathway, through the same angle, in the same direction and at the same time.
example of linear motion
an ice-skater gliding after they’ve completed a movement
a cyclist who stops pedalling
example of angular motion
when a gymnast performs a giant circle on a bar, the entire body rotates, with the axis of rotation passing through the centre of the bar.
in reference to angular motion, what is the difference between internal and external rotation?
internal rotation uses joints around which the rotational movement occurs.
external rotation occurs when body parts rotate around a point (axis of rotation) that occurs outside the body.
example of internal rotation
rotating your arm in backstroke (axis of rotation being your shoulder)
example of external rotation
rotating your racket in an overhead clear in tennis.
define general motion
combination of linear and angular motion. this is the result of the angular rotation of a number of body segments combining to produce linear motion of the body.
static balance
the ability to hold a stationary position.
- completing a handstand
- swimmer/ runner on the blocks at a start of race
- pyramid in cheerleading
dynamic balance
the ability to hold a moving position to execute an outcome.
- catching a wave
- riding a skateboard
- kicking a ball in soccer
external forces
results from interaction between the body and the environment. including;
- gravity
- friction
- air resistant
- water resistant
internal forces
structures of the body that interact to produce movement. eg muscles and tendons that act together to produce forces that cause that cause movement.
newtons 1st law
a body continues in its state of rest or state of motion unless acted upon by another force.
newtons 2nd law
the acceleration of a body is directly proportional to the force applied to it and inversely proportional to the mass of an object.
newtons 3rd law
for every action, there is an equal and opposite reaction.
define momentum
measure of amount of motion possessed by a moving body. is the product of mass and velocity.
define sequential movement
whereby the body parts involved in the performance move in sequence - beginning with the largest, slowest and strongest segments and working through to the smallest and fastest segments.
explain two forces which impact a projectiles flight path
- air resistance - the forces that are in opposition to the relative motion of an object as it passes through the air. without air resistance, a projectiles horizontal velocity would remain constant. projectiles can be impacted by head winds, tails winds or no wind.
- gravity - the downward force which bring projectiles back to the ground. it causes projectiles to accelerate towards the earth and is responsible for giving projectiles their parabolic path.
the path of a projectile is called a trajectory. explain two components which cause a trajectory to curve.
horizontal component and vertical component.
what are the three different flight paths of a trajectory?
- high trajectory: longer flight time (high jump)
- parabola trajectory: maximises horizontal distance (javelin)
- flat trajectory: shortest flight time (pitching a baseball)
3 factors that can determine the flight path of a trajectory
- angle of release
- height of release
- speed of release
describe the 3 angles of release
- greater than 45º- vertical velocity is greater than horizontal. increased height and flight time (NFL punt)
- 45º- vertical and horizontal velocity is equal. max horizontal distance attained (golf drive)
- less than 45º- horizontal velocity is greater than vertical. less height and flight time. less horizontal distance (lateral pass in rugby)
