Miomechanical Principles Flashcards
What are forces related to?
Mass and Motion
Miomechanics
Study of force that are applied to the outside and inside of the body and the body’s reaction to those forces.
What is included under laws of motion?
Law of Inertia, Law of Acceleration, Law of Action-Reaction
What does the laws of motion form?
The framework from which advanced motion analysis techniques are derived
What is Newton’s first law?
A body remains at rest or at a constant linear velocity except when compelled by an external force to change its state.
What is Newton’s first law called?
Law of Inertia
What is Newton’s first law in rotational application?
A body remains at rest or at a constant angular velocity around an axis of rotation unless compelled by an external torque to change its state
When is a body at static equilibrium?
when its linear and and rotational velocities are zero - the body is not moving
When is the body in dynamic equilibrium?
When its linear and/or rotational velocity is not at zero, but it constant.
In all cases of equilibrium, the linear and rotation ___________ of the body are at _______?
1) Acceleration
2) Zero
What is Inertia?
The amount of energy required to alter the velocity of a body
What is the inertia of the body directly proportional to?
Its mass (the amount of matter constituting the body
Center of gravity
Point which the effects of gravity are completely balanced
Center of mass
Point where the center of mass is evenly distributed in all directions.
Where is the center of mass in a human body in anatomic position?
Lies just anterior to the second sacra vertebra, but will change as the individual moves.
T/F: There is a center of mass in every major segment and its fixed?
True - Approximately at its midpoint
T/F: The center of mass within the entire lower extremity is fixed.
F: It changes with a change in spatial configuration of the segment.
T/F The Center of mass can be outside of the body for the entire lower extremity?
True
Mass moment of inertia?
A body is quantity that indicates its resistance to a change in angular velocity.
What does mass moment of inertia depend on?
Mass of the body and distribution of its mass with respect to the axis of rotation
Is human movement angular or linear?
Angular
What happens to the center of mass when a knee extends?
Moves farther from the hip - increasing its mass moment of inertia
Changing an entire limbs mass moment of inertia can affect?
Muscles force and joint torques necessary for movement
What happens when the knees are flexed and extended?
Flexed: Decreased mass movement of inertia
Extended: Increased mass movement of inertia
What happens when an individual reduces their their body mass moment of inertia?
Increased angular velocity
What is Newton’s 2nd Law?
The linear acceleration of a body is directly proportional to the force causing it, takes place in the same direction in which the force acts, and is inversely proportional to the mass of the body
What is Newton’s 2nd law called?
Law of Acceleration
What is the Rotational Application of Newton’s 2nd Law?
The angular acceleration of a body is directly proportional to the torque causing it, takes place in the same rotary direction in which the torque acts, and is inversely proportional to the mass moment of inertia of the body.
When forces acting on the body are zero and acceleration is also zero what is the body in?
Linear equilibrium
What is force measured in?
Newton
T/F: Law of acceleration defines a force-accerlation relationship.
True
In Newton’s second law, what does force represent?
Sum of, or net, forces acting on a body.
Angular acceleration of a body is directly proportional to….
the torque causing it.
What is momentum?
Quantity of motion possessed by a body
What is impulse?
Force applied over a period of time
