physic's

an object that is moving, they help to explain acceleration

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

any push or pull, ____ is a vector

quantity that has direction magnitude-size or length adds in a special way

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

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

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

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

speed and direction

the result of adding together two or more vectors

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

put tails at same point

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)

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

take the distance and divide by the time

speed at the moment in time

average velocity = displacement divived by time taken

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

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

_____ =change in velocity divided by the time taken

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

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

one moment of time shorter than any mesasurement of time

_____ of time has zero length

only two possible directions of motions
horizontal
vertical

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

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=

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

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

force exterted by a spring symbol: fsp->

force exerted by a solid that always opposes mortion

prevents an object from starting to slide

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

friction between a rolling object opposes a rolling object

force exerted by a liquid or gas that always opposes motion

force exerted by expelling gas or liquid at high speeds

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

net force is called

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

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

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

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

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

straightline through origin

every measureable quanity has only one unit

interpenetration of hills and valleys on surfaces

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

kinetic and rolling friction dont depend on speed

object moving at constant speed

acceleration always points towars the middle of the circle

same direction speeding up, deals with speed

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

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 w-omega

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

line around which an object is rotating

a single point

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

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

+ for counterclock wise, - for clockwise

angle between r axis and force

___ is located at center of gravity from one point

all objects have a singel point called

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)

the net force equals zero
the net torque equals zero- cannot rotate

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

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

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

____ are equal (at the bumpers)

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

mass times velocity

the more force you have the bigger the impulse

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

everything else

force one part of system exerts on another part of system

force enviornment exerts on a system

equals the sum of momentum of a 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

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

can normally be used in
collisions
explosions-situations where internal forces cause an object to suddenly split apart into two or more parts

objects stick together

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

is the ability to do positive work

is the ability to do work because of motion and speed

ability to do work because of height

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

ability to do work because of temperature

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

work done by external forces

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

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

the random motion of the atoms of a substance

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

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

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

boiling point of water 100 degrees
freezing point 0 degrees
absolue zero -273

absolute zero- 0
freezing point- 273
boiling point - 373

everything at same temperature

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

thermal energy that transfers froma hotter object to a cooler object

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

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

force divided by area

average pressure at sea level  atm

when a gas expands Wext is negative with heat
when a gas compresses Wext is positive

thermally insulated heat =zero delta Eth is positive

heat = zero delta Eth is negative temperature decreases