Studied by 0 people
Looks like no one added any tags here yet for you.
movement is
a change in position
how do we quantify movement
by where we are in space and how long it takes us to get somewhere
a change in position is called.
linear change
does linear = straight?
no
a change in orientation is called
angular change
most movement is
a combination of linear and angular change
linear motion
translation. change in position. move in the same direction
angular motion
rotation. change orientation. spin around the same fixed axis.
linear motion occurs when
all points on a body or object move the same distance, in the same direction, and at the same time
linear motion is also referred to as
translation
there are two types of linear or translatory motion
rectilinear and curvilinear
rectilinear motion
movement along a straight line
curvilinear motion
movement along a curved line
why is curvilinear motion considered a linear motion and not a rotational motion
because there is movement to a new position and we are not fixed to the same spot.
riding an elevator is an example of
rectilinear motion
throwing a ball straight forward, the path of the ball is an example of
curvilinear motion (comes down due to gravity)
kinematics tells us
how fast, how far, what direction the movement is
kinematics does not include
forces
linear motion occurs when
all points of the body or object move the same distance, in the same direction, and at the same time
kinematics is the description of
movements, without getting into what causes those movements
so linear kinematics is concerned with
linear motion
questions about speed, distance, and direction are part of
linear kinematics
mechanically, position is defined as
a location in space
position involves identifying
where a system is at the start and end of an action
position can be described in how many dimensions
one, two, or three (up/down, forward/backward, left/right)
to describe position, we need to identify
a starting point for movement so we can explore the direction of travel
to standardize the measurements we take, it is good to have a
fixed spatial reference system
the system commonly used is a
cartesian coordinate system
Cartesian Coordinate System. where is quadrant 1
top right
in quadrant one, x moves right and y moves up. this means
x and y are positive
where is quadrant two
top left
in quadrant two, x moves left and y moves up so
x is negative and y is positive
where is quadrant 3
bottom left
in quadrant 3, x moves left and y moves down so
x and y are negative
where is quadrant 4
bottom right
in quadrant 4, x moves right and y moves down so
x is positive and y is negative
movements that are in a single direction or planar can be analyzed in
2 dimensions. points of interest are x or horizontal direction and y or vertical direction
total length traveled is called
distance (l)
distance is what type of quantity
scalar
a change in position is called
displacement (d)
displacement is what kind of quantity
vector
basic unit of human movement is (for l and d)
meters (m)
what is speed (s)
change in distance over time
s =
(l2 - l1 ) / (t2 - t1)
speed is what type of quantity
scalar
velocity (v) is
change in displacement over time
v =
(d2 - d1) / (t2 - t1)
velocity is what kind of quantity
vector
the basic unit of speed and velocity is
meters per second (m/s)
when will speed and velocity of an object be equal
when distance traveled is the same as displacement
when will distance traveled be the same as displacemen t
when you move from point A to B in a straight line
can d ever be bigger than l
no
can l ever be bigger than d
yes
can speed every be greater than velocity
yes
can velocity ever be greater than speed
no
what is pace
a person's manner of walking or running
pace is the
change in time over change in distance
pace =
(t2 - t1) / (l2 - l1)
pace is
the inverse of speed
acceleration is
change in velocity
if velocity changes, the motion is characterized as
dynamic
what produces a change in velocity
forces
acceleration is the
change in velocity over tim e
a =
(v2 - v1) / (t2 - t1)
acceleration is what type of quantity
vector
the base unit of acceleration is
meters per second squared (m/s^2)
when velocity is constant, we are in a
static state
when velocity is changing, we are in a
dynamic state
acceleration can be
positive, negative, or zero
when is acceleration positive
v2>v1 (speeding up)
When is acceleration negative?
v2
when is acceleration zero
v2=v1 (no change in velocity)
so, the sign of acceleration can tell us
the state of the system
when we say a man traveled +50.0m. the + means
direction. up or right
when we say a woman walked at a rate of -3.0 m/s. the - sign means
direction. moving down or left
so the sign in front of velocity and displacement tells us
direction of movement
when we say acceleration is +3.7 m/s^2, we are saying
the direction is toward the right or up
so the sign from acceleration tells us
one of two things which needs to be clarified. either it tells us the state of motion, meaning if the system is slowing down to speeding up. it can also tell us direction
if we speed up to the right, what is the sign for direction of motion, state of motion, direction of push
+++
if we are not changing velocity but going to the right, what is the sign for direction of motion, state of motion, direction of push
+00
if we are slowing down but still moving to the right, what is the sign for direction of motion, state of motion, direction of push
+--
if we are speeding up but now going to the left, what is the sign for direction of motion, state of motion, direction of push
-+-
if we are not changing velocity but still going left, what is the sign for direction of motion, state of motion, direction of push
-00
if we are still going left but we are slowing down, what is the sign for direction of motion, state of motion, direction of push
--+
so, just to clarify. acceleration's sign can mean two things. this will be clarified in the question. it can either tell us state of motion (slowing down, speeding up) or it can tell us direction of motion (up, right, left, etc.)
...
what is a projectile
any object thrown, released, or dropped into the air or from a height
examples of projectiles
basketball, discus, high jumper, pole vaulter
a projectile is any object that is
moving through the air unassisted
projectiles are only under the influence of
gravity and air resistance
for our purposes, air resistance is
negligible
acceleration due to gravity
-9.81 m/s^2
what kind of acceleration is gravity
constant/uniform
in projectiles, the components that are analyzed are
vertical and horizontal
once a body is projected into the air, velocity is
changing
gravity only affects
vertical velocity
as a ball is thrown straight up into the air, what happens to its displacement
goes up, peaks, comes down (upside down u shape)
as a ball is thrown straight up into the air, what happens to its velocity
starts positive, reachers zero, goes to negative of what it started as ( opposite of / shape)
as a ball is thrown straight up into the air, what happens to its acceleration
constantly -9.81
as projectiles accelerate in free fall,
upward air resistance is created
air resistance is also called
drag
