biomechanics Flashcards
what does newtons first law of motion state
an object whether at rest of in motion, will continue in that state unless it is acted upon by a force strong enough to change its state or motion
what is an example of newtons first law of motion
A soccer ball wont move from its position unless a force acts upon it (the ball is kicked.)
what does newtons second law of motion state
the acceleration of an object is directly proportionate to the amount of force applied and takes place in direction in which the force is applied
what is an example of newtons second law
a netball will accelerate faster than a medicine ball (weighted ball) when thrown because it is lighter.
what does newtons third law of motion state
for every action there is an equal and opposite reaction.
what is an example of newtons third law
when you jump, you legs apply force to the ground, and the ground applies an equal and opposite reaction force that propels you into the air.
what is linear motion
linear motion is a one dimensional motion that travels a straight line. it occurs when all parts of object travels over the distance at the same time.
what is angular motion
angular motion is also known as rotary motion, it is evident when the body or an object turns around an axis of rotation. an example of this can be doing a somersault, a gymnast completing a bar routine or tumbling in a floor routine.
what is general motion
general motion is a mix of linear motion and angular motion. for example for a cyclist, as its arms are involved in linear motion, and its legs are involved in the angular motion (turning of the wheels)
what are the functions of levers
what is the first class lever
what is the second class lever
what is the third class lever
what are the 3 points that make up a lever
what is isometric force
isometric force is when a force is created but no movement is created. an example of this is calf stretches against a wall. another example of this is holding a plank
what is isotonic force
isotonic force is large enough to change the state of motion of an object (kicking a ball)
what is submaximal force
sub-maximal force is a performer that does not utilise all the force available to complete a task (throwing a tennis ball to someone 1m away)
what is maximal force
maximal force is achieved by a combination of perfect timing, maximal muscle contraction and excellent technique (throwing a ball from the outfield)
define the term force
any pushing or pulling activity which alters the motion of a body
what are examples of objects that are receivers of force in human performance
- baseball bat
- throw a shot put
- catching a ball
- the ground
(newtons third law)
what is force summation
force summation occurs when all body parts act simultaneously In practice, the strongest and lowest body parts around the centre of gravity (e.g. trunk and thighs) move first, followed by the weaker, lighter, and faster extremities.
what is simultaneous force summation, give a sporting example
- maximal force
- high jump
what is sequential force summation, give a sporting example
body parts move in a sequence to produce the desired degree of force
what is the difference between the two types of force summation
what are the four rules of sequential force summation?
order- the large muscles groups before the small ones
timing- each muscles are brought in at the same time
stabilisation- the foot plants on the ground in a shot put throw to then enable maximal force
what is angular motion
it is evident when a body or object turns about an axis of rotation.
what is moment of inertia
the resistance of rotating body to change, particularly during its resistance to beginning rotation.
what is angular velocity
time rate at which an object rotates, or revolves, about an axis, or at which the angular displacement between two bodies changes
what is high inertia
more force has to be applied in order to cause a rotation
what is low inertia
lower moments of inertia means that only low forces are necessary. Masses that are further away form the axis of rotation have the greatest moment of inertia.
what is high angular velocity
what is low angular velocity
what is the formula for angular momentum
what is projectile motion
what are the factors that effect the distance achieved by a projectile
- speed or velocity release
- angle of release
- height of release
- gravity
- air resistance
what is the velocity/speed of release
the speed at which a projectile is released or launched
what is the angle of release
is the angle of take-off of a projectile. theoretically the angle of release for achieving maximum distance is 45 degrees
what is the height of release
is the vertical height above the point of landing which a projectile is released or launched. for any given velocity and angle of release, as the height of release increases, the distance achieved increases.
what is gravity
gravity is a constant force that acts on all projectiles by pulling them towards the earth at the rate of 9.8 metres per second
what is air resistance
air resistance is the resistance to motion of a projectile created by the air through which the projectile must travel
what are the factors affecting air resistance
- the projectiles shape
- velocity
- increased velocity, increased air resistance
- mass or weight
what does it mean to use air resistance to gain an advantage
what is the projectiles shape
blunt-shaped objects passing through the air experience greater air resistance than streamlined tapered shapes. it is for this reason that aircraft are designed with a tapered front, narrow leading edges and a streamlines fuselage. this also applies to a design of racing cars and, more recently, bicycles.
what is the projectiles velocity
air resistance is greater at higher velocities. a ball thrown at high velocity will experience greater air resistance than a ball thrown gently. this is seen when throwing beach balls around.
what is the projectiles mass or weight
air resistance has a greater effect on lighter objects as opposed to heavier objects. this is seen when dropping objects of different mass and shape from a height
