Biomechanical principles Flashcards
BIOMECHANICAL MOVEMENT
what is newtons first law (law of inertia) ?
an object stays at constant motion unless acted upon by an external force
[ F=ma ]
e.g.
- rugby conversion kick
- football penalty
what is newtons second law (law of acceleration) ?
an object will accelerate in the same direction as the force is applied on it
[ F=ma ]
the amount of acceleration is directionally proportional to the force
e.g.
- passing in football
what is newtons third law (law of action/reaction) ?
for every action there is an equal and opposite reaction
e.g.
- 100m sprint (force into ground and more gained speed)
- rugby tackle (going for tackle, more force to win)
what is an unbalanced force?
forces acting on an object are unequal so the object moves in the direction of larger force
e.g.
tennis ball being returned after a serve
what is a net force?
the sum of all forces acting on an object
what is a reaction force?
the opposing force that acts on an object when its applying a force
definition of weight?
the force of gravity acting on an object
9.81 x mass = weight (N)
definition of balance?
all forces are equal, but they oppose each other in terms of direction therefore the object remains still/constant motion
e.g.
travelling at constant speed in middle of 100m sprint
definition of air resistance and what 4 factors affect it?
an opposing force which occurs when an object moves through the air
- velocity of object
- mass of object
- front cross-sectional area
- streamline shape
e.g.
cycling
1. the faster velocity, the higher AR
2. the heavier mass, the lower AR
3. the larger the area, the higher AR
4. smoother shape, the lower the AR
definition of friction and what 3 factors affect it?
an opposing force which occurs when two objects move over one another
- velocity of object
- mass of object
- smoothness of surface
e.g.
cycling and sprinting
1. the faster velocity, increases friction
2. the heavier mass, increases friction
3. the rougher the surface, increases friction
4 factors affecting stability
- base of support
- body mass
- centre of mass
- line of gravity
applied:
1. the larger surface area you stand on and cover as a wrestler the more stability you have
2. the heavier the more stability
3. the lower centre of mass the more stability
4. remain in the centre to keep stable
when are levers formed?
when we try to move objects by contracting muscles in order to move bones at a joint
what makes up a lever?
- lever arm
- fulcrum F (triangle)
- load L (arrow down)
- effort E (arrow up)
1 2 3
F L E
when is a first class lever used?
the fulcrum is placed in between the load and effort
e.g.
header in football
when is a second class lever used?
the load is placed in between the fulcrum and the effort
e.g.
jumping / running
when is a third class lever used?
the effort is placed in between the fulcrum and load
e.g.
bicep curl
shooting / striking
advantages of the lever systems
first class:
- mechanical advantage
- if the length of the effort arm is greater than the length of the load arm
second class:
- mechanical advantage
- a larger load can be lifted with relatively little force
third class:
- fast movement
disadvantages of the lever system
first class:
- mechanical disadvantage
- if the length of the load arm is greater than the length of the effort arm
second class:
- slower movement
third class:
- mechanical disadvantage
- a larger effort is needed to lift a relatively small load
