Chapter 2: Describing Objects in Linear Motion Flashcards
What branch of rigid-body mechanics is concerned with the mechanics of moving objects
Dynamics
What branch of dynamics is concerned with the description of motion (ie speed, velocity)
Kinematics
What type of motion do all points on the body move?
-same distance, same direction, at the same time
Linear motion (translation)
What type of motion is a staight line?
Ex: figure skater gliding across the ice
Rectilinear translation
What type of motion is a curved line?
Ex: Ski jumper during “jump” phase
Curvilinear translation
For both rectilinear and curvilinear translation, all points on a body/object move so that orientation of the object does not change and ALL points on the object move the same distance-The difference is the ___
Line (curved vs straight)
What type of motion (rotation) do all points on the body move through the same angle
-all points on body or object move in circles (or parts of circles) about the same fixed central line or axis
Angular motion (rotation)
A type of angular motion that is a giant swing or pirouette
Whole body rotation
What type of angular motion involved flexion, extension, adduction, abduction
Segment rotation
What type of motion combines angular and linear motion?
-Most common in sports and human movement, like peddling a bike or walking
General motion (mixed)
The 4 descriptors of linear motion
How far?
What direction?
How fast?
Speeding up, slowing down?
Term used to describe something identifying location in space
Position
A position that consists of starting line and finish line (+40m, -40m)
1 dimension
A position that consists of a goal line, sideline and Cartesian coordinate system
2 dimensions
A position that consists of ball on tennis court from baseline, from sideline, how high
3 dimensions
Both ____ and ____ measure a change in position (motion)
Distance and Displacement
What is the term used to describe the length of path traveled
Distance (scaler)
What term uses a vector (a number and direction), linear distance in a specified direction
Displacement
Which way is x-direction?
Horizontal
Which way is y-direction?
Vertical
What is a straight line between initial (start) and final (end)
Resultant
Both ____ and _____ measure rate of motion
-How fast the body is moving (meters/second=m/s)
Speed and Velocity
Equation for Speed (scalar) length of space traveled
speed= distance traveled (meters) / time taken (seconds)
Equation for Velocity (vector)
velocity= displacement (meters)/time taken (seconds)
____is rate of motion, _____is rate of motion in a ____ direction
Speed, velocity, specific
Rate of motion at an instant in time
-time duration very short
-change in position very short (interval of a race)
Instantaneous Speed or Velocity
Formula for average velocity
v= d/ change in t (or time taken)
Rate of change in velocity
-starts, stops, speeds up, slows down, changes direction
Acceleration
What type of acceleration is best described as: when acceleration is constant (constant force)
-allows for prediction of future position and velocity
-two many applications (vertical and horizontal motion)
Uniform acceleration
Two types of uniform acceleration: ____ and ____
Vertical motion and horizontal motion
____motion: gravitational force constant
a=g=-9.81 m/s squared (- downward)
Vertical motion
____motion: ignore air resistance
acceleration= 0 m/s squared
Horizontal motion
Vi and Vf describe what
initial velocity and final velocity
change in y describes what?
yi=_____
yf=____
y displacement
yi= initial position
yf= final position
g stands for what and what is the numerical part of this?
gravitational acceleration= -9.81 m/s squared
change in time describes what?
ti= ___
tf=___
time interval
ti= time interval
tf= time final
Formula for vertical velocity at the end of some time interval
vf=vi + g*change in time
Formula for vertical position at the end of some time interval
yf=yi+vi change in t +1/2g*(change in time)squared
Formula for calculating velocity at the end of some displacemnt (s)
vf squared= v initial squared + 2g* change in y
True or false: Horizontal velocity remains constant over time
True
True or false: Horizontal displacement depends only on time interval
True
True or false: Horizontal velocity remains constant over a displacement
True
A type of motion that describes: An object in the air acted on only by forces of gravity and air resistance
-Consider vertical and horizontal kinematics separately
-Apply appropriate equation of uniform acceleration for each direction
Projectile motion
Type of motion that describes a plane curve that mirrors symmetrical and U-shaped
Parabola
