Exam 1 - Biomechanics Basics and Terminology Flashcards
Mechanics
the study of forces and their effects
Kinematics
Branch of mechanics that deals with the geometry of the motion of objects (displacement, acceleration, velocity)
Kinetics
the study of relationships between the force system acting on the body and the changes it produces in body motion
Biomechanics
uses principles of mechanics for solving problems related to structure and function of biologic and physiologic systems
objective of biomechanics
to understand the loading condition of tissues and their mechanical responses
Scalars involve _______ only.
magnitude
examples of scalars
temperature, distance, speed, mass
Vectors involve _______ and ________.
magnitude and direction
examples of vectors
displacement, velocity, acceleration, momentum, force
Vectors are geographically represented by _______.
arrows
Distance is a _______ quantity.
scalar
Displacement is a _______ quantity.
vector
“How much ground an object has covered” during its motion.
distance
“How far out of place an object is” / overall change in position
displacement
Speed is a _______ quantity.
scalar
Velocity is a _______ quantity.
vector
formula for speed
distance/time
speed is ignorant of _______.
direction
Speed can be _______ or _______.
instantaneous or average
“how fast an object is moving”
speed
rate at which an object covers distance
speed
formula for velocity
displacement/time
Velocity is _______ aware.
direction
“the rate at which an object changes its position”
velocity
to maximize velocity, must maximize amount _______ from original position
displaced
the rate at which an object changes its velocity
acceleration
formula for acceleration
change in velocity/time
_______ has to do with changing how fast an object is moving.
acceleration
if an object is not changing its _______, then the object is not accelerating.
velocity
Acceleration is a _______ quantity.
vector
The direction of the acceleration vector depends on two things:
Whether the object is speeding up or slowing down
Whether the object is moving in the + or - direction
Mass is a _______ quantity.
scalar
Momentum is a _______ quantity.
vector
_______ refers to the amount of substance within an object.
mass
Because _______ has direction, it can be used to predict the resulting direction of objects after they collide, as well as their speeds.
momentum
quantity of matter composing an object
mass
grams or kilograms are examples of _______.
mass
mass is often confused with _______.
weight (involves force)
formula for momentum
p = m * v
doubling the mass without changing the velocity of an object results in a _______ of the momentum
doubling
_______ is an action (push/pull) upon a body causing it to deform or move
force
force is measured in _______
Newtons (N)
force is a _______ quantity.
vector
One _______ is the amount of force required to give a 1kg mass an acceleration of 1m/s2 (squared)
Newton
The _______ of an object is the force of gravity acting upon that object
weight
The _______ of an object refers to the amount of matter that is contained by the object.
mass
Convert 10 Newtons to Pounds.
10 Newton = 1 Kilogram = 2.2 Pounds
Weight is _______ on the poles of the earth.
higher, objects are closer to the center of the earth’s mass
formula for force
force = mass * acceleration
According to Panjabi & White, how many Newtons of force are required for 1mm of posterior to anterior shear?
260 Newtons
resistance to having it’s state of motion changed application of a force
inertia
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force
Newton’s first law
AKA for Newton’s first law
Law of Inertia
The acceleration of an object depend directly upon the net force acting upon the object and inversely up the mass of the object
Newton’s second law
AKA for Newton’s second law
Law of Force and Acceleration
According to Newton’s second law, if the state of motion of the system changes, then a _______ must have been applied.
force
According to Newton’s second law, if the state of motion of the system changes, then a force must have been applied. The observed change is motion is called _______.
acceleration
formula for Newton’s second law
F = m * a
Same as the equation for force.
For every action, there is an equal and opposite reaction.
Newton’s third law
AKA for Newton’s third law
Law of Action and Reaction
_______ is the force that resists the sliding of two objects in contact.
friction
_______ stress: the intensity of force perpendicular to the surface on which it acts
normal stress
_______ stress: the intensity of force parallel to the surface on which it acts
shear stress
_______ _______: exists when two contacting surfaces are not currently sliding relative to each other but do possess the potential for movement
static friction
_______ _______: type of friction that exists when the two surfaces are already sliding relative to each other
kinetic friction
AKA for kinetic friction
dynamic friction
forces that elongate or pull things apart
tensile forces
forces that compact an object
compressive forces
_______ is the magnitude of applied force acting over a given area (P=F/A)
pressure
pressure is measured in
Newtons/meter2 (squared) or pascals (Pa)
1 Pa = ?
1 N/m2
_______ is the displacement of an object by the application of a force
work
formula for work
Force x Distance
work can be _______ or _______
positive or negative
The energy an object possess due to motion
kinetic energy
_______ motion is the motion of one object with respect to a reference object.
relative motion
What are the 4 categories of movement?
discrete, continuous, repeated discrete, serial
What category of movement has a definite beginning and end point?
discrete
What category of movement has cycles of motion performed repeatedly with no well-defined beginning or end points?
continuous
What category of movement appears continuous but at the end of a stroke the body is not in a position to perform the next stroke?
repeated discrete
What category of movement appears to be somewhat continuous in nature but are really a combination of discrete motions?
serial
_______ movements result from major muscle group activity involving large muscles
gross
_______ movements are precise and controlled by small muscle groups or individuals
fine
the path of motion around a fixed axis and therefore in a circular path
angular motion
time rate of change of angular position of a rotating body
angular velocity
time rate of change of angular velocity of a rotating body
angular acceleration
the point about which a body rotates
axis of rotation
perpendicular distance from an axis of rotation to a line along which a force acts
lever arm, force arm, moment arm
product of force and lever arm; the tendency of an eccentric (off center) force to rotate an object around an axis
torque
fulcrum is between the effort and the load/resistance
type 1 lever
load/resistance is between the fulcrum and effort
type 2 lever
effort is between the fulcrum and the load/resistance
type 3 lever
ratio of the motive force (effort) to a given resistive force
mechanical advantage
formula for moment arm (M)
M = force * lever arm distance
the point that represents the average location of a system’s mass
center of mass
the point at which the force of gravity seems to be concentrated
center of gravity
