Exam 1 Deck Flashcards
Axis
a line passing perpendicularly through the plan
Sagittal plane rotations occur about a ………axis
medial - lateral axis
Frontal plane rotations occur about an …….axis
anterior posterior
Transverse Plane rotations occur about a ……….axis
longitudinal
Plantar
Dorsal
P- bottom of foot
D- Top of foot
Superior is
relation to torso
Frontal Plane Joint Movements
Elevation -
Depression -
Valgus -
Varus -
Elevation - elevate/lift shoulders
Depression - Lower shoulders
Valgus - Pushes knee into each other
Varus - Knees outward (air between them)
Transverse Plane Joint Movements
medial/lateral rotation
Look up
Biomechanical Measures
Kinematics or Kinetics (meaning for both)
Kinematics - (description of motion) –>Angular (Joint angles) or –>Linear (walking in a straight line)
Kinetics - (measure of forces) –>Linear (A force - ground reaction forces) or –>Angular (Torques - cause a rotation)
Linear Motion
translation of a body
all parts of the body travel exactly THE SAME distance, in THE SAME direction, at THE SAME time.
Rectilinear -
Curvilinear -
R - is a straight line
C - Curved line
angular orientation is always maintained
Angular Motion -
all parts of the body travel through the same angle, in the same direction, in the same time about an axis of rotation
General Motion -
Combination of linear and angular kinematics
Ex: Rotation of wheels results in linear motion of the bike.
Weight is a ……..
Force
- Length is measured in
- Mass is measured in
- Time
Weight is mass with gravity
- Meters m
- Kilograms kg (MASS DOES NOT CHANGE)
- Sec s
Kinematics Dimensions and Units Derivative measures LECTURE 3
Kinetics =
study of forces acting on body
Statics =
Study of force and torque when a system in state of constant motion
At rest = constant velocity = no acceleration
Dynamics =
Study of force and torque when a system in state of changing motion
System not in steady state motion = acceleration is non zero
Force
- effect of one body on another
- a push or pull applied to an object
Examples:
- Weight (the attraction to earth)
- Bone on Bone (really cartilage to cartilage)
- Muscle (the pull of sarcomeres, via tendons)
External Forces
Forces that act on a “system” as a result of its interaction with the enviroment surrounding it
Internal Forces
Forces that at within the “system” whose motion is being investigated
How to calculate FORCE
F = mass x acceleration
Units are N = Newtons
Scalar
Vector
Magnitude + Direction =
S - Quantity with a magnitude (Distance) Height will not change
V - Quantity with magnitude and direction
= Scalar
Linear Motion -
Kinematics =
Travels in a straight line - translation
Body parts travel same distance direction and time
= Description of motion = Linear Kinematics
Distance and Displacement
Units:
Scalar or Vector?
Equation:
Typical Units - cm, m, km
Distance - Scalar - Length of a path from the starting to finishing position
Displacement - Vector - Change in location of a point expressed as a length and direction from the starting position to the ending position
D = Df - Di
Speed vs. Velocity
Scalar or Vector?
Units:
Equation:
Speed - Scalar - Rate of distance traveled over a period of time
Velocity - Vector - Rate of displacement over a period of time in a given direction
Velocity = displacement/change in time
Units - m/s, rad/s, deg/s
Average vs. Instantaneous
Instantaneous - calculates the velocity at existing or measured at a particular instant
Example:
- Driving down 34 from greeley to loveland
- Out of town speed limit is 65 mph
- As you go faster the speed on your speedometer is your instantaneous speed
Average Velocity = V/T
Acceleration -
Scalar or Vector:
Equation:
Units:
Vector
- Describes rate of change of linear and angular velocity wrt time
- Rate of change in velocity over time
Acceleration = Vf - Vi/change of time
Units: m/s^2, rad/s^2, deg/s^2
Linear Kinematics
Scalar
Vectors
Scalars - Distance and Speed
Vectors - Displacement and Velocity and Acceleration
Velocity =
Acceleration =
Instantaneous velocity =
Instantaneous Acceleration =
V = rate of change of position wrt time
A = rate of change of velocity wrt time
Instantaneous velocity = is reflected by the slope of the position curve at some instant in time
Instantaneous Acceleration = in reflected by the slope of the velocity curve at some instant in time
Changes in Curve Slide
Slope =
number which describes the change in a curve
Weight is a………
Force
Uniformly Accelerated Motion (Projectile Motion)
3 equations must have constant veritable acceleration and horizontal velocity
Speedofrelease:mostimportant
IncreasesinVH
IncreasesinVV
V H increasedistance.
IncreasesinVV increasetimeofflight. Heightofrelease
Heightofrelease
Increasestimeofflight.VH andVV remainsame
timeofflight.VH andVV remainsame
Angle of release
Affectsratioofhorizontalandverticalvelocities
Overall,effectisminimalsinceincreasesinoneare
offsetbydecreasesintheother.
Optimum angle of release
If take off height = landing height
Optimum angle of release is always 45 degrees
Angular Position (theta)
Measure can be taken
Units:
Measure can be taken
Line wrt line
Joint angle
Line wrt plane segment angle
Units: radians, degrees, revolutions
Radian
A radian is defined as the ratio between the circumference of a unit circle and the length of its radius
Angular Displacement
Moving from different points
Angular motion is not static
Difference between initial and final positions
Units: radians
Angular Velocity
A vector
Rate of change of angular position over time
Magnitude and directions
Rad/sec
How fast it’s going around a point or curve
Angular Acceleration
rate of change of angular velocity wrt time
• (a vector) (Magnitude & Direction)
Arc Length is
Displacement
Tangential Velocity
Linear tangential velocity is the linear speed of any object moving along a circular path
Tangential Accleration
The linear acceleration that describes the rate of change in magnitude of tangential velocity
Linear and angular acceleration
• An object must be forced to follow a curved path
(remember inertia and Newton’s 1st law – more to come)
• A change of direction (see arrows) represents a
change in velocity (a vector quantity). • If there is a change in velocity, there is a
resulting acceleration.
Watching the ball as it moves example (being on the ball)
Centripetal Force
Center seeking force
Direction of centripetal force is always 90° to the motion of the body
Towards the axis of rotation
Along the radius
F = MA
Relationship between Velocity and Acceleration
When velocity is constant acceleration is constant (0)
How is radius effected when velocity and acceleration is constant?
Smaller radius the
Faster the velocity
If a velocity changes a direction it has an acceleration to it
If velocity is constant in the horizontal motion what is acceleration……
Zero??????
