Biomechanics Flashcards
what is newtons 1st law
Law of intertia
“ a body continues in a state of rest or motion in a straight line, unless compelled to change that state by an external force “
what is newtons 2cnd law
law of acceleration
“ the rate of momentum of a body is proportional to the force causing it and the change that takes place in the direction in which the force acts “
what is newtons 3rd law
law of reaction
“ to every action force, there is an equal and opposite reaction force “
what is the definition of inertia
resistance of a body ( object ) to change its state of motion e.g. having to apply more force to a weighted ball
application of newtons 1st law
when kicking a rugby ball of a tee, the rugby ball will remain at rest on the tee until an external force is applied by the rugby players foot to the ball
application of newtons 2cnd law
when kicking a rugby ball of a tee, the greater the size of the force applied by the player to the ball, the greater the rate of change momentum and acceleration towards the post. The ball will accelerate in the same direction as the force applied towards the post.
application of newtons 3rd law
when kicking a rugby ball of a tee, a forward and upward “action force “ is applied to the ball from the players foot. The ball will apply an equal and opposite force to the players foot.
what is a scalar quantity
a scalar quantity is when measurements are described in terms of just their size or magnitude
what are examples of scalar quantities
- speed
- distance
define speed
the rate of change of position and can be calculated by distance divided by time
speed is in metres per second
define distance
the length of the path of a body follows when moving from one position to another
what is the centre of mass ( coM )
the point of balance in the body
usually between the hip region ( naval )
males coM is usually higher than females
what are the four factors affecting stability
1) the height of coM - lowering coM will increase stability
2) position of line of gravity - should be central over the base of support becomes, and the stability increases
3) area of the support base - more contact points, the larger base of support becomes , stability increases
4) mass of performer - greater mass , more stability because of increased inertia
what is the lines of gravity
the lines that extends vertically downwards from coM and determines if the body is stable or not
how can you maximise stability
- crouched position - low coM
- large base support
- line of gravity falls within base of support
- weight- high mass
how can you minimise stability
- raise coM
- lower base of support
- weight
what are the two main functions of levers
- to generate muscular effort to overcome a given load
- to increase the speed of a given movement
what are the 3 main components of a lever
- fulcrum ( pivot )
- resistance ( load to be moved )
- effort ( source of energy )
define the fulcrum
part of the lever system
point about which the lever rotates
define what resistance is
in the lever system
the weight to be moved by the lever system
define what effort is
part of the lever system
the force applied by the use of the lever system
what is a lever
bones
- rigid structures which roate around a fixed point
- known as the fulcrum
what is the fulcrum
in the human body the fulcrum is the joint