Exam 1 Flashcards
________ is the study of structure and function of biological systems by means of the methods of ________.
Biomechanics; mechanics
Biomechanics is the study of ______ and their effects on living ______
forces; systems
what is a force
a push or pull
what is the SI measurement for force?
a newton
how do we graphically represent a force’s magnitude and direction?
vector
what does the length of the vector represent? What part of the vector represents the direction?
- size of the force
- direction
what is a scaler? examples?
a quantity that has magnitude but no direction; mass volume density (a known amount)
forces acting within the object or system whose motion is being investigated
internal forces
t/f internal forces do not change the center of mass
true
what are two examples of internal forces?
tensile forces & compressive forces
pulling force that acts on the internal structure (object under tension)
tensile forces
pushing forces that act on the ends of an internal structure (object under compression)
compressive forces
forces that act on an object as a result of its interaction with the environment surrounding it
external forces
what is an example of an external force and why?
measuring weight because weight is the force of gravity acting on an object
weight = ?
mass x gravity
what is the unit for mass?
kg
what does ‘g’ represent
acceleration due to gravity (9.81 m/2 squared)
t/f kilogram is the unit for mass and not for weight
true
how do you calculate weight?
mass x speed of gravity
forces that occur between objects that are touching one another
contact forces
contact forces can be either ____ or _____
solid or fluid
what is an example of a contact force
air resistance, water resistance, the ground
what are the 2 components of contact force?
- normal contact force aka normal reaction force
2. friction
which contact force acts perpendicular to the surfaces in contact
normal contact force
the line of friction is _____ to the 2 surfaces in contact & _____ motion (or sliding) between the _____
- parallel
- opposes
- surface
what forces are responsible for human locomotion?
friction forces
dry friction between two surfaces that are not moving
static friction
static friction is also referred to as _____ friction
limiting
Dynamic friction is also called _____ friction and ______ friction
sliding, kinetic
which type of friction acts between two moving surfaces?
dynamic friction
friction is proportional to what?
normal contact force (pressure)
the greater the ______ between two objects in contact the greater the friction
pressure
what is the outcome of adding vectors called?
the resultant force
the vector addition of all the external forces is the …
net force
adding vectors on the same line
colinear force
vectors that are not on the same line but in the same plane
concurrent forces
what is the method for graphically representing a co-planar vector
tip to tail method
what are the three rules for tip to tail method
- draw vectors to scale
- draw vectors at the appropriate angle
- can add many vectors in any order
trigonometric vector resolution
geometry of triangles
when do you use the pythagorean theorem?
for right triangles ONLY
when do you use the law of sines
to determine angles in non-right triangles
when do you use the law of cosines
to determine magnitude in non-right triangles
what is the acronym for remembering graphing calculator equations when solving for right triangles
SOHCAHTOA
when solving for the vertical component, always use ____ component
cosign
what are the three types of motion
- linear motion
- angular motion
- general motion
define linear motion
uniform motion of the body; all parts move in the same direction at the same speed
body parts don’t move _____ to each other
relative
what are the two types of linear motion
a. rectilinear (straight path)
b. curvilinear (arched path)
rotation around a central imaginary line called the axis of rotation; this line is perpendicular to the plane of motion
angular motion (rotary motion)
the axis of rotation in angular motion may be ______ or ______
internal or external
general motion consists of _____ and _____ motion
linear and angular
the study of shape, form, pattern, & sequencing of linear movements through time
linear kinematics
two branches of linear kinematics
qualitative: ID major joint motions sequencing & timing of body movements (no numbers)
quantitative: specific time, velocity (numbers)
define position
location in space
a ____ is only a quantity, while a ____ needs displacement
scaler; vector
rate of motion is known as
speed (distance/time)
rate of motion in a specific direction is known as
a vector
t/f velocity is a vector
true
changing the ______ or _____ changes the velocity, since it is a vector
displacement or time
what is the unit for velocity and speed
meters to seconds
what is the equation for speed
stride length x stride frequency
distance between ipsilateral [same side] heel strikes; measured in ______
stride; meters
what does stride frequency represent
per second (Hz)
what is the equation for velocity
change in velocity/change in time
a body launched into the air is influenced by ____ and _____ resistance only
gravity; air resistance
path of projectile through its flight
trajectory
what is the trajectory influenced by
- projection angle
- projection speed
- projection height
angle from the horizontal at which a projectile takes off
projection angle
in projection angle, the ____ influences the ____ of the projectiles path
angle; shape
three types of projectile angles
- vertical
- oblique
- horizontal
takeoff velocity of the body in motion
projectile speed
the projection ____ determines the ____ of the trajectory
speed; size
uniformly accelerated motion is the ______ motion of a projectile
vertical
in uniformly accelerated motion there is constant _______; the most common found is ______
acceleration; gravity (9.81 m/s2)
when a projectile is launched into the air it is _________ at 9.81 m/s2 until it reaches it’s ____ _____
decelerating; peak height
angular kinematics
motion around an axis
_____ are axes of rotation
joints
angular kinematics requires measurement of angles using
protractor
goniometer
electrogoniometer
computer
2 types of angles you can measure
- relative (looking at position of one body segment relative to the other)
- absolute: angle of a body segment relative to a reference line
the difference between the final and initial angle of segments is known as
angular displacement (moving in a circular path)
going from 150 deg. to 90 deg. is known as a _______ displacement
negative
when a joint is fully extended it is at ___ degrees
0
one circle = ___ degrees, ___ radians, ____ revolution
- 360 degrees
- 2(pi) radians
- 1 revolution
1 revolution = ___ rad
6.28
1 rad = _____ degrees
57.3
what is the equation for angular velocity? what is it similar to?
omega (w) = 0 (theta) / change in time (t);
velocity = distance/time
what is the equation for angular acceleration?
a= change in w / change in t
the greater the _____ a given point on a rotating body is located from the axis of rotation, the greater the ____ _______ undergone by that point
distance; linear displacement
what is the equation for linear velocity? what is the rule associated with this equation?
VL = r x w
**w must be in radians/second
we can maximize the striking force by increasing what?
angular velocity or the radius
linear velocity is important in what types of activities
striking
acceleration tangent to the circular path of a point on a rotating object
at (tangential acceleration)
acceleration toward the center of a curve
ar (radial acceleration)
