Biomechanical principles and levers Flashcards
linear motion
And in a straight or curved line, with all body parts moving the same distance at the same speed in the same direction
inertia
Resistance an object has to change in its state of motion
Newton’s first law of inertia
a force is required to change the state of nation
in a penalty, the ball (body) will remain on the spot (state of rest) unless it is kicked by the player (an external force).
Newton second law of acceleration
The magnitude (size) and direction of the force determines the magnitude and direction of the acceleration
When the player kicks (force) the ball during the game, the acceleration of the ball (rate of change of momentum) is proportional to the size of the force.
So the harder the ball is kicked, the further and faster it will go in the direction in which the force has been applied
Newton’s third law of motion
For every action (force) there is an equal and opposite reaction (force)
when a footballer jumps up (action) to win a header, a force is exerted on the ground in order to gain height. at the same time, the ground exerts an upwards force (equal and opposite reaction) upon the player.
ground reaction force
Equal and opposite force exerted on a performer who applies a muscular force on the ground
e.g. sprinter off the blocks
scalar quantity
when measurements are described in terms of their size and magnitude
speed + distance
speed
the rate of change of position
speed =distance/time
distance
length of a path a body follows when moving from one position to another
distance=speedXtime
centre of mass
point of balance
line of gravity
this is the line extending vertically downwards from the centre of mass
factors affecting stability
The height of a centre of mass.
Position of the line of gravity.
Area of the support base.
Mass of the performer
levers
fulcrum- the point about which the lever rotates
resistance-the weight to be moved by the lever system
effort- the force applied by the user (muscle) of the lever system
first class lever
effort- fulcrum- resistance
flexion and extension of neck
extension of elbow
second class lever
fulcrum- resistance- effort
plantar-flexion of ankle
third class lever
fulcrum- effort- resistance
hip, knee, elbow flexion
mechanical advantage
force (effort) arm is longer than the resistance arm
can move large loads
requires little force
small range of movement
difficult to generate speed+ distance
mechanical disadvantage
resistance arm is greater than the force/ effort arm.
cannot move heavy loads
fast
large range of movement
