Linear kinematics
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Transcript Linear kinematics
ESS 303 – Biomechanics
Linear Kinematics
Linear VS Angular
Linear: in a straight
line (from point A to
A
point B)
Angular: rotational
A
(from angle A to
angle B)
B
B
Kinematics VS Kinetics
Kinematics: description of motion
without regard for underlying forces
Acceleration
Velocity
Position
Kinetics: determination of the underlying
causes of motion (i.e., forces)
Linear Kinematics
The branch of biomechanics that deals
with the description of the linear spatial
and temporal components of motion
Describes transitional motion (from point
A to point B)
Uses reference systems
2D: X & Y axis
3D: X, Y & Z axis
Linear Kinematics
B
A
What About This?
B
A
What About This?
B
A
Some Terms
Position: location in space relative to a
reference
Scalars and vectors
Scalar quantities: described fully by
magnitude (mass, distance, volume, etc)
Vectors: magnitude and direction (the
position of an arrow indicates direction and
the length indicates magnitude)
Some Terms
Distance: the linear measurement of space
between points
Displacement: area over which motion
occurred, straight line between a starting and
ending point
Speed: distance per unit time (distance/time)
Velocity: displacement per unit time or
change in position divided by change in time
(displacement/time)
What About This?
Distance & Speed
B
Displacement & Velocity
A
Graph Basics
B (4,3)
Y
A (1,1)
C (5,2)
D (2,1)
X
SI Units
Systeme International d’Units
Standard units used in science
Typically metric
Mass: Kilograms
Distance: Meters
Time: Seconds
Temperature: Celsius or kalvin
More Terms
Acceleration: change in velocity divided by change in
time
(Δ V / Δ t)
(m/s)/s
Acceleration of gravity: 9.81m/s2
Differentiation: the mathematical process of
calculating complex results from simple data (e.g.,
using velocity and time to calculate acceleration)
Derivative: the solution from differentiation
Integration: the opposite of differentiation (e.g.,
calculation of distance from velocity and time)
Today’s Formulas
Speed = d / t
Velocity = Δ position / Δ t
Acceleration = Δ V / Δ t
Slope = rise / run
Resultant = √(X2 + Y2)
Remember: A2 + B2 = C2
SOH CAH TOA
Sin θ = Y component / hypotenuse
Cos θ = X component / hypotenuse
Tan θ = Y component / X component
θ
Sample Problems
A swimmer completes 4 lengths of a
50m pool
What distance was traveled?
What was the swimmer’s displacement?
Move from point (3,5) to point (6,8) on a
graph
What was the horizontal displacement?
What was the vertical displacement?
What was the resultant displacement?
Sample Problems
A runner accelerates from 0m/s to
4.7m/s in 3.2 seconds
What was the runner’s rate of acceleration?
Someone kicks a football so that it
travels at a velocity of 29.7m/s at an
angle of 22° above the ground
What was the vertical component of
velocity?
What was the horizontal component of
velocity?