ap physics exam unit 1-4

work formulas

not ones with p

power formula

work/time

force * displacement/time

force * velocity

conservative forces

work is 0 over a closed path → starts where it begins (example a circle)

work done is independent of the path taken

work done by a constant force

-change in potential energy

types of collisions

elastic

completely inelastic

partially inelastic

elastic collision

no energy was lost in environment

ex. bouncing a ball

momentum=final momentum

KE = final KE

completely inelastic collision

lost energy during path

ex. dropping a rock on the ground

momentum=final momentum

KE =/ final KE

all other collisions for momentum

momentums equal each other but kinetic energy is not equal to each other

momentum formula

mass * velocity

unit of momentum

kg * m/s

linear momentum

same direction as object’s velocity

add up momentums to find total momentum

change in momentum → p final - p inital

inertia

resist change in motion that is measured by mass

as mass increases what happens to inertia

inertia increases

impulse

integral of force exerted on object over time interval

area under force vs time graph

change in momentum

same direction as net force exerted on object

impulse momentum theorem

average impact force

average acceleration

change in velocity/change in time

kinetic friction

static friction

circular motion acceleration

velocity of banked curve

how to solve newton’s 2nd law

1. choose system

2. draw all forces on system

3. choose coordinate system with one axes in direction of acceleration

4. set up 2nd law in both direction

tensions

assume string has negligible mass

strings only pull, they never push

always pull in the direction they are oriented

newton’s 3rd law

object a pulls on object b, then object b pushes or pulls on object with same force but opposite direction

work in terms of potential energy

force * change in u

force in terms of potential energy

force = -derivative of u

potential energy in terms of universal gravitation

potential energy

mgh

height for potential energy

final - initial height

resistive force

force that resists the motion of an object

example of resistive force

air resistance, drag force

resistive force formulal

-kv

terminal velocity equations

mg/k

mg/k (1-e^-k/m*t)

gravitational field

what does it mean if fg is the only force exerted on object

ag = g

weight

mg

apparent weight

m (fg - ag)

weightless

apparent weight=0

no exerted force and fg is only force (free fall)

equivalence principle

inertial mass and gravitational mass are the samein

inertial mass

resists changes in motion using newton’s second law and finding a

gravitational mass

mass attracts other mass to it using the gravitational force

uniform sphere

gravitational force but r is distance between center of sphere and object

partial mass formula

how can newton’s second law be written in terms of momentum

collision time

more time means less impact force

bouncing

greater change in velocity and momentum

what does it mean for greater momentum change

greater impulse and impact force

conservation of momentum

if no external forces, total momentum is constant

internal forces

forces without human force

external

forces with human force

how to solve conservation of momentum problems

choose system where p is constant

before/after pic

write algebraic expressions for p1 and p2 → solve for unknown

external force acts in dimension

system’s p changes in dimension

remain constant in other directions

center of mass

location that behaves as if all system’s mass were concentrated there

center of mass formula