
an object that is moving, they help to explain acceleration
motion diagram

focus's on a single point, assumes object is a single point (example: door handle)
particle model

any push or pull, ____ is a vector
force

quantity that has direction magnitudesize or length adds in a special way
vector

quantity in which direction is not important (example: takes me 5 seconds to walk to the end of the hallway)
scalar

an arrow from a reference point to a point of interest (maybe chosen everywhere)
postion vector

arrow is a vector symbol arrow always points to the right, for r1 the magnitude is 2m and the diection is 45 degrees
vector symbol

in a straight line path from an earler point to a later point
displacement vector

speed and direction
velocity

the result of adding together two or more vectors
resultant

pick a scale for the length of the arrows
draw an arrow representing one of the vectors
place another arrow representing on of the other vectors with its tail at the first arrows tips
contiued with step 3 until all the arrows tips are at the arrows tails
the resultant is the arrow from the tail of the first to the tip of the last
graphical method of adding vectors (tip to tail method)


put tails at same point
complete the parallelagram draw in a side parallel, to a and b with the same length
the resultant goes from the point it started to the opposite side (A+B)
parallelogram method of adding vectors

a negative vector has the same magnitude but the exact opposite direction
vector subtracting

take the distance and divide by the time
average speed

speed at the moment in time
instantaneous speed

average velocity = displacement divived by time taken
velocity of average speed

____ points in the same direction as displacement, in motion diagrams displacement vectors will be used to represent average velocities
average velocity

the rate of change of velocity
1.) speed up
2.) slowing down
3.)changing direction
acceleration

_____ =change in velocity divided by the time taken
average acceleration

if the acceleration is facing the same direction of velocity it is ____
speeding up

if the acceleration is facing a different direction of velocity its ____
slowing down

one moment of time shorter than any mesasurement of time
an instant

_____ of time has zero length
a moment

only two possible directions of motions
horizontal
vertical
one dimension linear motion

amount of change in velocity in one unit (one second)
acceleration

if gravity is the only force acting on an object the objuect with have a downward acceleration of 9.8 m/s

the highest point of acceleration=
9.8m/s

usually called normal forces perpendicualr forces symbol is n(with arrow above)
compression forces

force exerted by a stretched elastic object as it tries to return to its natural shape (bungie cord ropes steel cables) symbol: T>)
pulls inwards at both ends
tension forces

force exterted by a spring symbol: fsp>
spring force

force exerted by a solid that always opposes mortion
friction

prevents an object from starting to slide
static friction

opposes a sliding object we will assume fk does not change with speed
kinetic friction

friction between a rolling object opposes a rolling object
rolling friction

force exerted by a liquid or gas that always opposes motion
drag

force exerted by expelling gas or liquid at high speeds
thrust

the net force of air pressure on most objects is close to zero so we will ignore air pressure
air pressure

net force is called
resultant force

picture showing all the forces acting on a certain object
for the particle model
free body diagram

the tendency of an object to resist changes in its velocity and all objects have inertia bowling ball has more inertia than a basketball
inertia

measure of an objects inertia the units of mass are kg, g, mg
mass

is the force of gravity on an object units of weight newtons
weight

an objects mass is the same everywhere, an objects weight depends on location

straightline through origin
direct proprtionality

every measureable quanity has only one unit
si units

interpenetration of hills and valleys on surfaces
surface roughness

chemical bond for only when they are touching, if you have two very smooth surfaces you can get alot of chemical bonds and large friction
chemical bonding

kinetic and rolling friction dont depend on speed
fsmas, fk, and fr are all proportional to the normal forces

object moving at constant speed
uniform circular motion

acceleration always points towars the middle of the circle

same direction speeding up, deals with speed
acceleration parallel

change of direction, if a perpendicular is opposite then it is slowing down, if direction of a perpendicular shows direction of object is curving
acceleration perpendicular

r axis is towards center of the circle
t axis tangetial to circle with positive t in counterclockwise direction
z axis perpendicular to the plane of motion

force towards the center of the circle would be static friction

rate of going in a circle most common unit rpm, symbol womega
angular velocity

direction of a force and where you apply the force makes a difference
torque

line around which an object is rotating
axis of rotation


turning effect of a force, radial forces cannot create torque only tangential forces can
torque

distance from axis to point where force is applied times the tangentail component of force
torque

+ for counterclock wise,  for clockwise
torque

angle between r axis and force
phi

___ is located at center of gravity from one point
force

all objects have a singel point called
center of gravity

to calculate torque due to gravity, the entire wieght of the object can be assumed to pull down at the cg for a symetic uniform object cg is at the objects geometric center

if an object is at rest and supported at a single point the cg must be either directly below the support point

is what changes an objects rotation(speeding up or slowing down)
torque

the net force equals zero
the net torque equals zero cannot rotate
static equalibrium

pick an object to focus on
draw a free body diagram of this object
choose a pivot point
calculate torque about this pivot for all the forces
solve
applying sum of torque = zero

forces always occur in pairs, they are in opposite directions
forces always exerts a force back on one another
action reaction pair

states that every action has an equal and opposite direction reaction
whenever one object exerts a force on a second object the second object exerts an equal and opposite force back on the first object
newtons third law

____ are equal (at the bumpers)
contact forces

depends on acceleration, larger acceleration usually menas more internal damage (on the drivers)
internal forces

mass times velocity
momentum

the more force you have the bigger the impulse
impulse momentum theorum

one or more objects we consider as a unit, a group of objects we wish to study
system

everything else
enviornment

force one part of system exerts on another part of system
internal force

force enviornment exerts on a system
external force

equals the sum of momentum of a system
total momentum system

if the net external force on system equals zero a systems total momentum remains constant
internal forces cannot change total momentum of a system

choose a system
does net external force equal zero
choose inital and final times
then solve p^{}_{f = }p_{i}
using the law of conservation of momentum

if delta t is very small the impuse and delta p is very small
if there is firiction then they would be different, the net system would not equal zero

if delta t is small enough total momentum of the system is conderved even if they net external force doesnt equal zero
impulse approximation

can normally be used in
collisions
explosionssituations where internal forces cause an object to suddenly split apart into two or more parts
impuls approximations

objects stick together
inelastic collision

postive work means F is enhancing the motion
negative work means F is opposing motion

is one in which the work done by this force just depends on inital and final postion not depended on the path
conservative force

is the ability to do positive work
energy

is the ability to do work because of motion and speed
kinetic energy

ability to do work because of height
gravitational poetential energy

ability to do work because of the stretching or comressing of an elastic object
elastic potential energy

ability to do work because of temperature
thermal energy

ability to do work because of chemical reactions

are always associated with conservative forces
when the ball was thrown kinetic energy increased while chemical energy decreases
potential energies

work done by external forces
external work

choose a system to focus on when using Ug, earth must be part of the system
chooose initial and final times
calculate external forces Wext
calculate change in each system
solve the energy equation
steps in using energy equation

creates thermal energy
where delta s is the total distance traveled against Fdiss, it is not dissplacement
with _____ both objects must be included in the system bc they both gain thermal energy
dissipative forces

the random motion of the atoms of a substance
thermal motion

rate of doing work or the rate of gaining or using up energy
power

energy of a substance due to thermal potion two parts of Eth
kinetic energy of the atoms
a form of Us due to the stretching and compressing of chemical bonds
thermal energy

is a measure of the aberage random kinetic energy of the atoms of a substance
temperature

boiling point of water 100 degrees
freezing point 0 degrees
absolue zero 273
celsius scale

absolute zero 0
freezing point 273
boiling point  373
kelvin scale

everything at same temperature
thermal equalibrium

transfers from hotter objects to the cooler objects because of atomic collisions or radiation
thermal energy

thermal energy that transfers froma hotter object to a cooler object
heat

amount of heat needed to increase 1kg of the material by 1 degrees celsius
can be thought of as thermal inertia
specific heat

the more atoms there are in a kg of material the more heat it requires to increase the temperature

force divided by area
pressure

average pressure at sea levelĀ atm
atmospheric pressure

when a gas expands Wext is negative with heat
when a gas compresses Wext is positive
first law of thermodynamics

thermally insulated heat =zero delta Eth is positive
adiabatic compression

heat = zero delta Eth is negative temperature decreases
adiabatic expansion

