biomechanics Flashcards
what is a force
a push or a pull that alters the state of a body
what is inertia
the resistance of a body to change its state of motion , either at rest or whilst moving
what is velocity
the rate of change in displacement
what are newtons three laws
law of inertia , law of acceleration & law of reaction
what is newtons first law
law of inertia
what is newtons second law
law of acceleration
what is newtons third law
law of reaction
what is newtons first law of inertia
a body will continue in a state of rest or uniform velocity unless acted upon by external force
- greater the mass , greater the inertia therefore the greater fore needed to change the body’s state of motion
what is newtons second law of acceleration
a body’s rate of change in momentum is proportional to the size of the force applied and it acts in the same direction as the force applied
- the more force , the more acceleration and the bigger the change in momentum
what is newtons third law of reaction
for every action force applied to a body, there is an equal and opposite reaction force generated by the object back towards the body
how does mass effect inertia
the greater the mass of an object, the larger its inertia therefore a greater force is needed to change its state of motion
how do you calculate velocity
displacement / time taken
how to calculate momentum
mass x velocity
how to calculate acceleration
(final velocity - initial velocity) / time taken
how to calculate force
mass x acceleration
what are the two types of forces
internal and external
what are internal forces
forces generated by the contraction of skeletal muscle
what are external forces
forces that come from outside of the body and acts upon it
what are the 5 effects of force
- can create motion
- can accelerate a body
- can decelerate a body
- can change the direction of a body
- can change the shape of a body
what is net force
the sum of all forces acting on a body
if net force is zero
the forces are balanced
if the net force is present…
… the force are unbalanced and the body is accelerating/decelerating/ changing shape or direction
what does a positive net force mean
body is accelerating
what does a negative net force mean
body is decelerating
what are the two vertical forces
weight and reaction
what is weight
gravitational pull that the earth exerts on a body
how does weight act
downwards force from the bodys centre of mass
how does reaction act
upwards force from the bodys point of contact with surface
what are the two horizontal forces
friction and air resistance
in what direction does friction act
same direction as the direction of motion from the point of contact
what affects friction
- roughness of the surface
- roughness of contact surface
- temperature
- size of normal reaction
in what direction does air resistance work
against the direction of motion from the bodys centre of mass
what affects air resistance
- velocity
- shape of body
- frontal cross section of body
- smoothness of surface
what does it mean if net force is zero
body is at rest/ travelling at uniform velocity
how can an athlete increase/maximise their power
through weight/plyometric training - uses the speed and force of different movements to increase muscle power
more muscle power - more action force therefore more reaction force/acceleration
what is centre of mass
the point where all forces are balanced- dependant on the distribution of body mass
how can the centre of mass be manipulated
by altering the body shape ie stretching/bending
what is stability
the ability of a body to remain at rest and resist motion
what is stability affected by
• mass of body
• line of gravity
• points of contact
• height of COM
• base of support
how does mass effect stability
more mass - more stable
how does centre of mass affect stability
the lower the COM- the more stable
how does line of gravity effect stability
the closer the line to centre of mass - the more stable ie lean forward
how does the base of support effect stability
wider the base - more stable
how does points of contact effect stability
more points of contact - more stable
what is the line of gravity
an imaginary line that extends from the centre of mass to the floor
how does like of gravity and base of support link
the more central the line is to the base of support - more stable
what is 123FLE
1 class, 2 class, 3 class
fulcrum, load, effort
what are levers
systems that are the coordinated of our bones and muscles - to primarily make movement
what are the functions of levers
• to generate muscular effort to overcome a given load
• to increase the speed of a given movement
what are the components of the lever in the body
lever (bone)
fulcrum (joints)
effort (muscular effort used)
load (weight/resistance)
what is a first class lever
when the fulcrum is in the middle of the effort and load
what is a second class lever
when the load is in the middle of the fulcrum and effort
what is a third class lever
when effort is in the middle of the fulcrum and the load
when is there a mechanical advantage
when the effort arm is longer than the load arm (second class levers)
when is there an mechanical disadvantage
when resistance is more than effort 3rd class levers)
