Biomechanics

• biomechanics is a branch of kinesiology concerned with the behaviour and function of the body when it is acted upon sports
• a force is a push or pull measured in Newtons
• internal forces arise within the body or system
• external forces originate outside of body or system
• inertia is the property of matter that causes an object to resist any changes of motion
• a lever is a simple machine capable of altering the direction and magnitude of a force
• linear motion is when a body moves the same distance and direction in the same amount of time
• angular motion is movement of a body about an axis due to eccentric force
• resultant force is the difference between the two forces that cause linear motion
• centric force is applied directly through centre of body resulting in linear motion only
• eccentric force is directed through a point other than the centre of body resulting in rotational movement
• torque is the turning or twisting effect caused by eccentric force
• static system involves body or object being in a state of constant, unchanging motion
• dynamic system is one that experiences a change in the rate it is moving due to forces applied
• stability is the quality, state, or degree of being stable and resisting change in motion
• balance is an even distribution of mass enabling someone to remain steady
• mass is the quantity representing amount of matter in a particle or object
• centre of mass is an imaginary middle point around which the mass of an object/body is balanced
• base of support is the supporting area beneath something
• the base of supports limits are defined by points of contact with supporting surface
• what is an example of intentional instability

  a football player close to end zone may become unstable so they are tackled into endzone
• the moment of inertia is the resistance to angular motion
• law of inertia: body remains in a stationary position or at a constant velocity unless a force is exerted upon it
• law of acceleration: the greater the mass of an object, the more force required to move object at same rate
• law of action-reaction: when a body/object exerts a force on another, the reaction force is equal and opposite in magnitude and direction to applied force
• class 1 lever: fulcrum is located between force and load
• a seesaw or crowbar is a class 1 lever
• class 2 lever: load is located between force and fulcrum
• a door or wheelbarrow is a class 2 lever
• class 3 lever: force is located between fulcrum and load
• a broom or fishing rod is a class 3 lever
• production of maximum force requires use of all possible joints
• production of maximum velocity requires use of joints from largest to smallest
• impulse-momentum relationship means the greater the applied impulse, the more momentum and velocity
• direction of application of applied force is similar to newton’s third law, movement occurs in direction opposite of applied force
• production of angular motion occurs by application of eccentric force causing turning effect called torque
• conservation of angular momentum is when the body stays rotating while airborne
• principle 1 is stability
• principle 2 is production of maximum force
• principle 3 is production of maximum velocity