biomechanical principles Flashcards
(43 cards)
newton’s first law
•law of inertia
•an object will continue in as state of constant velocity until compelled to change by an external force
newton’s second law
•law of acceleration
•an object will accelerate proportional to the force acting and in the direction of that force
• mass x acceleration = force
newton’s third law
•law of reaction
•for every action there is an equal and opposite reaction
force definition
a push or pull that tends to alter the state of motion of a body
momentum force
the amount of motion possessed by a moving body
acceleration definition
the rate of change in velocity
weight definition
the force that the earth exerts on the mass of a body
velocity definition
rate of change in displacement of the shortest route from A to B
force equation
force= mass x acceleration
momentum equation
momentum = mass x velocity
acceleration equation
acceleration = force / mass
or
acceleration = change in velocity / time
velocity equation
velocity = displacement (distance) / time
centre of mass definition
A point at which mass is distributed evenly in all directions.
factors effecting centre of mass
•distribution of mass
•movement of limbs
•uniformity if shape
centre of mass and distribution of mass
In the human body centre of mass is constantly moving depending on the distribution of the mass.
centre of mass and uniformity of object
In a uniform object (something with the same density from the centre to all parts), like a shot, the centre of mass remains in the middle at all times.
centre of mass and movements of limbs
In unique scenarios, like the Fosbury Flop on the right, the centre of mass may move outside of the physical body.
stability
a measure of how a body is moved from a position of equilibrium or balance.
line of gravity
an imaginary lie extending vertically downward to the ground from the centre of mass
base of support
the area enclosed by the points of contact with the ground.
factors effecting stability
- Low centre of mass – The lower we are to the ground and the shorter the line of gravity, the more stable we are. Think a rugby player in a tackle
- Large base of support and points of contact with the ground – The bigger the base of support the more stable we are. Think of a headstand compared to a handstand.
- Large mass – The larger our mass the larger our stability. Try shifting a heavy object off a plateau compared to a lighter one
- Line of gravity in the middle of base of support – Again consider a handstand, as soon as you lean you legs one way or the other you are likely to be unstable.
balanced forces
When two or more forces acting on a body are equal in size but opposite in direction. All forces cancel out .
unbalanced forces
When two or more forces acting on the body do no cancel out. This means a net force acts.
net force
The overall force acting on a body when all forces are considered. Also know as the resultant force.
