Lecture #3 (Kinematics & Kinetics) Flashcards
True or false:
Sport activities are static in nature.
False
In the scheme of biomechanics, what is under the static heading?
Equilibrium, line of gravity, and center of mass
In the scheme of biomechanics, what is under the dynamic heading?
Kinematics and Kinetics
In the scheme of biomechanics, what falls under the kinematics heading?
Linear or angular displacement, velocity, & acceleration
In the scheme of biomechanics, what falls under the kinetics heading?
Force, impulse, momentum, work, energy, power, mass, joint torque, moment of intertia, etc.
What are the three things that can influence movement in the body?
Sensory, motor, and biomechanical factors (other factors are present as well such as friction, velocity, momentum, inertia, impulse, etc.)
When you move, what moves outside your center of gravity and what tries to catch up?
When you move, your line of gravity (LOG) moves outside your COG, and your base of support (BOS) tries to keep up—i.e. when you’re running
What is a state of stability in which motion is restricted or prevented?
Fixation (think of walls, floors, etc.)
True or false:
Muscles can only provide motion at its distal end.
False–this is because the muscle can fixate one end and then move either its proximal or distal attachment.
What is the description of motion without regard for the forces producing the motion?
Kinematics
What are the two types of motion?
Linear (translation) and angular (rotary)
What type of motion does our joints utilize?
Angular (rotary)
What are the two types of linear motion?
Curvilinear= all points move the same distance Rectilinear= all points move in a straight line
What is angular movement?
Movement around a fixed point (center of rotation/axis) in a curved path
True or false:
Each point during an angular movement moves through the same angle and same distance from the fixed point, but the different points move different distances in the same amount of time.
True–think of elbow flexion. When you flex your elbow, the angle of you arm is the same; however, your wrist moves a greater distance than your forearm.
What is the length of the path that an object moves?
Distance traveled
What is the straight line distance between a starting and ending point?
Displacement
What is the rate of motion? How is this typically averaged?
Speed–typically distance/time such as mph
What is the rate of motion in a specific direction? How is this measured?
Velocity–displacement/time
What is the rate of change of velocity?
Acceleration
What is a real-world example of the distance between speed and velocity?
Map Quest would utilize speed–the distance you travel is averaged out over time (that’s how you get your time of travel). A radar gun would utilize velocity because it is measuring the speed of something in a instantaneous moment.
True or false:
Motion direction is always an indication of acceleration direction.
False–it is not always indicative of acceleration direction. Think of slowing down, the acceleration is opposite to the direction that is being traveled.
What is a projetile?
An object that is given velocity
What is kinetics?
Forces that cause linear motion (such as work, energy, and power)
What is Newton’s First Law?
Law of Inertia: a body remains at rest or in uniform motion until an outside force acts on it.
What is the conservation of momentum?
A product of mass and velocity–this is why it’s easier to run and jump rather than standing and jumping because your body is already moving
What is Newton’s Second Law?
Linear acceleration of an object is directly proportional to the force causing it—the acceleration occurs in the same direction in which the force was applied, and inversely proportional to the mass of the object
What is impulse?
Force over time–its what is used to change momentum
What is Newton’s Third Law?
For every action there is an equal and opposite reaction
True or false:
Forces occurs in pairs.
True–that’s how we get opposite forces (think of gravity–there is always a reactive force in the opposite direction to keep us from falling)
True or false:
A kinesiological evaluation is primarily qualitative?
True
What are the 3 components of a kinesiological evaluation?
1) Describing skill/breaking it down into its elements
2) Evaluating the performance of the skill (determing whether and how related anatomical and mechanical principles have been violated)
3) Prescribing corrections based on appropriate identification of causes
When correcting a something due to a kinesiological evaluation, what is the term for correcting the motion before injury? After injury?
Before= prevention After= rehab
During the kinesiological analysis of a skill, it is important to note the primary purpose of the skill as one of four things:
Speed, speed & accuracy (most sports), accuracy, or form
True or false:
Most sport skills have both a simultaneous (segments move as one) and sequential (segments move in orderly fashion) nature of motion.
True
During a kinesiological analysis (specifically the mechanical analysis), what is the underlying mechanics when the person: regains stability/attain mobility? An example?
Balance–jump stop or track start
During a kinesiological analysis (specifically the mechanical analysis), what is the underlying mechanics when the person: travels? An example?
Locomotion–walking, running, skipping, etc.
During a kinesiological analysis (specifically the mechanical analysis), what is the underlying mechanics when the person: height, range, & accuracy? An example?
Projection–Pole vault, long jump, or throwing
During a kinesiological analysis (specifically the mechanical analysis), what is the underlying mechanics when the person: objects or resistance? An example?
Manipulation–Weightlifting or throwing
During a kinesiological analysis (specifically the mechanical analysis), what is the underlying mechanics when the person: uses speed, power, and force? An example?
Maximun Effort–sprinting, power lifting, and blocking
When an athlete has a valgus collapse, what do we focus on rehabing and strengthening?
Hip abductors, hamstrings, and hip external rotators
What is weakness of a muscle because it is too long (stretched) to create peak force?
Passive insufficiency
What is weakness of a muscle because it is too short to create peak force?
Active insufficiency
What occurs when the muscle has the highest amount of cross-bridge formation?
Ideal resting length
