KIN 216 linear kinematics. projectile motion- quiz 1

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