Studied by 1 person
1 in = _____ cm
2.54 cm
1 mile = ____ km = ____ m
1.609 km, 1609 m
Proximal
In proximity to or closer to. Generally meaning closer to the torso.
Distal
Distant or further away. Generally meaning further from the torso.
Sagital
Divides into right and left halves
Frontal
Divides into front and back halves
Transverse
Divides into top and bottom halves
Movement occurs in the plane that it is ____ to.
Parallel
What type of exercises occur in the sagittal plane?
Situps Back extensions Bicep curls Running
What type of exercises occur in the frontal plane?
Jumping jacks Side bends Lateral dumbbell raises
What type of exercise occurs in the transverse plane?
Anything that involves rotation
What type of motion occurs in the sagittal plane?
Flexion/Extension
What type of motion occurs in the frontal plane
Adduction/Abduction, side flexion, inversion/eversion
What type of motion occurs in the transverse plane
internal/external rotation, horizontal flexion/extension, and supination/protination
What axis of motion corresponds with the sagittal plane?
Mediolateral Axis
What axis of motion corresponds with the transverse plane?
Superior-inferior Axis
What axis of motion corresponds with the frontal plane?
Anterior-Posterior Axis
What kind of activities are primarily planar?
Running, cycling, cartwheeling, and a softball pitch
What kind of activities are multiplanar?
Tennis serve, baseball pitch, and roundhouse kick
The mass of an object is determined by the amount of _________ in the object, and is measured in ___.
matter, kg
What 2 things does mass determine?
Measure of inertia
Determines the strength of gravitational attraction
Weight is a ________ and is measured in _. The equation for weight is ___________.
force, N Fg=W=mg
1 lb = ____ kg
0.455 kg
An object's ______ is the same everywhere, whereas it's ______ changes depending on where it is (eg. moon vs earth).
mass, weight
Mechanics
Analysis of the motion of an object and the forces acting upon the object
Biomechanics
Application of principles of mechanics to the study of living organisms
What are the two main subfields of biomechanics?
Rigid Body Biomechanics Deformable Body Biomechanics
What are the two main divisions within Rigid Body Biomechanics?
Statics Dynamics
Statics
The study of systems in a state of equilibrium (at rest or in a constant state of motion)
Forces are balanced = equilibrium
Dynamics
Interested in changing systems Broken down into two major areas: Kinematics and Kinetics
What are the two main divisions within Dynamics?
Kinematics Kinetics
Kinematics
The study of motion WITHOUT consideration of the CAUSE eg. speed
Describing and measuring human movement by focusing on the type of motion, the direction, and the quantity of the motion without regard for the forces that may produce that movement
Kinetics
The study of the CAUSE of motion (forces) eg. muscle force
Deals with forces that produce, stop, or modify motion of bodies as a whole or of individual body segments
Reference Frames (Cartesian Coordinates)
System describing a body's location in space (aka coordinate system)
Direction (3 axes)
Location (point of origin) Follows right hand rule (pointer finger x, middle y, thumb z)
Right Hand Rule
(pointer finger x, middle y, thumb z)
An angle CCW from the x-axis is _. An angle CW from the x-axis is _.
positive, negative
Vector
Fully described by both magnitude and direction (how big and what is direction)
Displacement Velocity Acceleration Force
Tip to Tail Method
Method of vector addition where one can add any two vectors by placing the tail of one so that it meets the tip of the other one
Vector Specified Two Ways:
Directly: magnitude and direction (A and theta)
Indirectly: X and Y components (xA and yA)
REMEMBER on Vectors
Magnitude sign is ALWAYS POSITIVE
Direction sign depend on reference (components sign pos/neg based on how vectors points)
Scalar
Fully described by magnitude (how big)
Distance Speed Maass Energy Temperature
Vector Equality
Two vectors are considered equal if they possess the same magnitude and direction
Commutative law of addition
When vectors are added together, the sum is independent of the order of addition
Resultant
A vector that represents the sum of all individual vectors acting upon a system
What are the 7 steps of multiple-vector composition?
Draw vectors in coordinate system, with tails at the origin
Break them down: turn each vector into x and y components
Add up all the x's= Rx
Add up all they y's= Ry
Put them back together again: draw Rx and Ry from tip-to-tail and compose them into the final R
Use Pythagorean theorem to find magnitude (POSITIVE)
Use tan-1 to find direction (NEGATIVE OR POSITIVE)
Position (P)
Location in space
Use a vector to describe a body's position, P, in the frame of reference (magnitude + direction)
∆P = "change in position" = displacement ∆P = P (final) - P (initial)
Displacement
Change in position of an object (in a specific direction i.e. 5 miles Northeast, or by X and Y components i.e. 4 miles E and 3 miles N)
Vector > specify as magnitude in a specific direction
∆P = "change in position" = displacement ∆P = P (final) - P (initial)
Distance
How far the object traveled to get from P (initial) to P (final)
Scalar > actual route taken
T/F Distance is always greater than the magnitude of displacement
F
Rates
How fast something is changing
Rate of change = ∆ something / ∆ t
Ie. Units = liters/min or m/s
Velocity
Rate of change of position (displacement/time) Vector [m/s]
Vavg = ∆P /∆t ∆P = displacement P(final)-P(initial) ∆t = change in time t(final)-t(initial)
Speed
Rate of change of distance Scalar > only informs how fast, no direction m/s
Savg = d/∆t
SPEED and VELOCITY are NOT THE SAME
Acceleration
Rate of change of velocity Vector [m/s2]
Aavg = ∆V / ∆t ∆V = V(final) - V(initial)
Acceleration directiions
Positive acceleration (+ direction) ∆V is pos, V value is increasing so f > i
Negative acceleration (- direction) ∆V is neg, V value is decreasing so f < i
If the V value increases, then acceleration is _. If the V value decreases, then acceleration is _.
positive, negative
tangent
A line in the plane of a circle that intersects the circle in exactly one point.
Distinguish between average and instantaneous rates
Slope between two time points gives average rate Slope at a time point gives instantaneous rate
Instantaneous speed/velocity
The rate of motion at a given instant in time (delta t becomes very small)
T/F with a linear velocity, Vavg = Vinstantaneous
T
Acceleration
slope of the time-velocity curve
Velocity
slope of the time-position curve
Change in position
area under the time-velocity curve
Change in velocity
area under the time-acceleration curve
Constant acceleration (flat slope) results in a ________ change in velocity.
linear (velocity changes at a constant rate)
Constant velocity (flat slope) results in a ________ change in displacement.
linear (displacement changes at a constant rate)
A linear change in velocity results in a _______ change in displacement.
non-linear (slope is not constant)
Uniform acceleration (eg. gravity) can predict __________ and ____________.
displacement, velocity
Slope
Rise over run
∆ vertical value / ∆ horizontal value
Projectile
A body in free fall that is subject only to the forces of gravity and air resistance (neglected)
Why do we analyze the horizontal and vertical components of projectile motion independently?
The vertical component is influenced by gravity, the horizontal component is not
Vertical projectile motion relies on:
Constant (yA = -9.81 m/s) Symmetry (when appropriate)
Symmetry in upward projectiles
patter of change in vertical position of a projectile is SYMMETRICAL ABOUT THE PEAK
for symmetry need initial positive yVi (moving up)
Projectile trajectory
Motion in both x and y directions Parabolic shape (curved, symmetrical) Influenced by initial projection speed, projection angle, and relative projection height
What does the shape of a trajectory depend on?
Projection angle
Initial conditions determine motion that a projectile will have:
TRAJECTORY: Projection speed > size Projection angle > shape Relative projection heigh > location
If want to max time of flight or heigh reached:
Increase projection angle Increase projection speed Higher release (projection height)
If want to minimize time of flight:
Decrease projection angle Increase projection speed
If want to max horizontal displacement:
Projection angle should approach 45 degree Increase projection speed Higher release (projection) height
Categories of Forces
Every force has one property from each category:
PUSH or PULL forces CONTACT or NON-CONTACT forces EXTERNAL or INTERNAL forces
ie. Gravity: pull, non-contact, external People: push, contact, external
Internal forces
Act completely within defined system
Can cause the object to change shape but cannot produce any changes to body's COM without an external force
Something INSIDE system applies a force to something else INSIDE system
External forces
Act on the system from the outside
Causes changes to a body's motion
Something OUTSIDE system applies a force to something INSIDE system
Free Body Diagram (FBD)
Diagram showing vector representations of all the external forces acting on a defined system
First law of uniformly accelerated motion (vertical velocity)
Second law of uniformly accelerated motion (vertical position)
Third law of uniformly accelerated motion (vertical velocity)
yVf = yVi + (ya)(tf)
Yf = Yi + (yVi)(tf) + (1/2)(ya)(tf2) 3.yVf2 = yVi2 + (2)(ya)(∆ Y)
The horizontal _______ of a projectile is constant. Therefore, ___________ is zero.
velocity, acceleration
3 Equations for the horizontal motion of a projectile (uniform velocity)
Xf = Xi + (xVavg)(∆t)
xVf = xVi = Constant
a = 0
3 things projectile trajectory is it influenced by?
Initial speed Projection angle Relative projection height
What are the 7 steps of the problem solving strategy for projectiles?
Write down which variable you need to know
List all known variables
Break up initial velocity into horizontal and vertical components
Figure out which equations allow you to solve for the unknown variable from the known variables
Rearrange the equation to isolate the desired variable
Plug in the known variables
solve.
Trajectory shape depends only on projection _________.
angle
Relative projection height = ?
Relative projection height = (projection height) - (landing height)
Contact forces vs. Non contact forces
CONTACT forces: between objects touching each other
NON CONTACT forces: eg. gravitational force
Equation for the force of gravity (weight)
W = Fg = mg
If only given initial velocity, which direction do you analyze to determine the time of flight of a projectile?
Vertical
Net force
The vector addition of all the external forces acting on an object
Inertia
A resistance an object has to change in motion, specifically a resistance to change in a body's velocity; resist acceleration
Applies to bodies at rest, moving linearly, and rotating
Quantitively measured by an object's MASS (units kg)
Has mass then has inertia
Mass is ____________ related to resistance to change in motion (Inertia).
directly
Momentum definition and equation
The quantity of motion that an object possesses
relates to effort needed to stop a motion
An objects linear momentum is related to its mass (m) and Linear Velocity (V)
L = mV
Still object (V = 0 ) has no momentum
Newton's first law is the law of _, the second is the law of _, and the third is the law of __________.
inertia, acceleration, reaction
Newtons 1st law
"The Law of Inertia"
An object at rest stays at rest and an object in motion stays in motion with the same velocity unless acted upon by an unbalanced force
Conservation of momentum
ie. drinking coffee while sitting in a moving car
ie. horizontal motion of a projectile
Newtons 1st Law: Conservation of Momentum
Formula: L = mV
If ΣF = 0 then L constant, mV constant ∆L = 0, ∆ (mV) = 0
Still object (V = 0 ) has no momentum
Newton's 2nd law
"The Law of Acceleration"
The acceleration of an object is directly proportional to the net force exerted on it (and inversely proportional to its mass)
ΣF = mA
Note
Flashcard