Biomechanics Flashcards
(17 cards)
Define linear motion
Motion in a straight or curved line where body moves in same direction e.g. 100m sprint
Explain first law of motion - inertia
•’the resistance an object has to a change in its state of motion’
•an object will remain still until at rest or continue to move in a certain direction until an external force is put on it
•the bigger the mass - the more force will be required to change an object/body’s state of motion
Explain second law of motion - 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’
•force = mass x acceleration
Explain third law of motion - action/reaction
•’to every action (force), there is an equal and opposite reaction (force)’
•all about what happens when 2 forces meet
•action = reaction - always in pairs
•ground reaction force: force exerted on the ground by the body in contact with it
explain centre of mass
•point of balance
•body is an irregular shape + is constantly moving - centre of mass changes
1) height of the centre of mass: lowering the CoM will increase stability
2) position of the line of gravity: should be central over the base of support to increase stability
3) area of the support base: the more contact points, the larger the base of support becomes = increase stability
4) mass of the performer: often the greater the mass of a performer, the more stability there is because of increased inertia
Define fulcrum
The point about the lever rotates
Define resistance
The weight to be moved by the lever system
Define effort
The force applied by the user (muscle) of the lever system
Define first class lever
The fulcrum lies between the effort and resistance - head/neck, elbow extension
Define second class lever
The resistance is between the fulcrum and effort - ankle
Define third class lever
The effort is between the fulcrum and the resistance - everything else
Define force arm
The length of the line between where the fulcrum and effort are labelled
Define resistance arm
The length of the line between where the fulcrum and the resistance are labelled
Define mechanical advantage
Where the force arm is longer than the resistance arm - 2nd
Define mechanical disadvantage
Where the resistance arm is longer than the force arm - 1st/3rd
Adv/disadv of 2nd class
Adv - can generate much larger forces, has to lift the whole body weight
Disadv - slow with a limited range of movement
Adv/disadv of 1st/3rd class
Adv - large range of movement and any resistance can be moved quickly
Disadv - cannot apply much force to move an object
