biomechanics (SAC 1) Flashcards
newtons laws: law of inertia
- a body will remain at rest or in a uniform motion in a straight line unless acted upon by an external force
e.g 1. a ball projected into the air will continue travelling straight without gravity
e.g 2. soccer ball will not move until a player enacts force on it
newtons law: law of acceleration
- a force applied to an object will produce a change in motion in the direction of the applied force that is directly proportional to the size of that force
(increased force = increased acceleration)
(decreased force = decreased acceleration)
newtons law: law of action and reaction
- for every action there is an equal and opposite reaction
(two objects come in contact they exert forces that are equal in size but opposite in direction)
e.g running we push down and back with our feet and the surface pushes back)
types of force: friction
- when two surfaces come in contact with each-other, opposes the motion of an object
- to overcome friction you must increase force
e.g studs (increase friction between boots and grass)
types of force: air & water resistance (drag force)
- will always slow down a projectile in motion, opposes object direction slowing it down
- increased speed = increased drag
factors - the speed the object is travelling
how to minimise - technique and clothing
types of force: gravitational force
- force of attraction between 2 bodies/objects
- caused of object to fall down
types of force: inertia
- tendency for a body to resist a change in it’s state of motion
(greater mass = greater inertia = greater force needed to change it’s state)
e.g a wet football requires greater force to kick due to increased mass
factors influencing motion
mass - amount of matter of an object
weight - gravitational pull on an object
inertia - reluctance to change state of motion
force - push or pull
linear motion
- straight line
e.g skiing (downhill/fixed position)
angular motion
- rotation around an axis (spinning around an axis)
e.g rotational dive, somersault
torque
force x lever arm
- measure of turning affect, dependant on the force applied and the distance from an axis
(greater torque = greater angular acceleration)
angular momentum, angular velocity & moment of inertia
angular momentum - total motion of the rotating body (remains constant) (product)
moment of inertia - the resistance of an object to change it’s angular motion
e.g spreading out after somersault increases M.O.I
angular velocity - velocity at which we are rotating or spinning
e.g tuck in to go faster (bring mass closer to axis)
angular velocity and moment of inertia are inverse of each other
projectile motion: HAS
- higher the release the further the projectile should travel
- when speed and angle release remain the constant = longer flight time
- best angle of release is 45 degrees
- greater force applied, the greater the speed and the projectile will go further
conservation of momentum
- can only occur with a collision
- no external forces acting, states total momentum of the system before the collision is equal to the total momentum after the collision
e.g spin bowler in cricket has less momentum compared to a pace bowler and therefore the batsman must hit it harder
summation of momentum
- the sequential movement of multiple muscle groups to perform a certain action
= greater force production
e.g To throw a discus lower body having a good base of support with your legs and then rotating your hips. Through rotating your hips the rest of your body rotates along with it, with your upper body following the rotation of your lower body.
