AP Physics 2 Full Year

Expansion means there is ____ work

NEGATIVE, gas has to do work against its surroundings

Isothermal Expansion

PV=PV, No change in temperature or internal energy, so W=-Q. Graph is downward parabolic and it’s slow movement of pistons with insulation or water bath.

W= 3/2nRT

Isobaric Expansion

Constant Pressure, horizontal line. Positive work and piston is free to move

Q= 5/2nRT because work is negative and it would be delta U - W

Isochoric/volumetric Expansion

Vertical line, volume same so no work. Delta U = Q and piston is locked in place

Adiabatic

Fast expansion so no escape of heat, meaning no Q. Delta U =W

Temperature is proportional to…

Delta U and sqrt(v_rms)

Radiation emission proportion

T^4 is proportional to frequency

Heat lost and gain

Use mc delta T equals -mc delta T

Pressure

F/A, use absolute not gauge. Pab = Po+ pgh

Heat transfer by…

Conduction, convection, and radiation

In written FRQs, remember…

Units, conversions, all formulas with substitution, DIRECTION (negative work, momentum, etc)

At a constant volume and pressure ( a single state) delta U equals

3/2PV

If product of PV is less,

Temperature decreased, meaning delta U increased and then based on the type of compression you can determine the signs of W and Q

The entropy of a full system always

Increases

Reaching thermal equilibrium is a _____ process

Irreversible, increases entropy

Mass does NOT affect ____

Temperature gain

A higher c means

The material maintains heat longer but takes longer to heat up

Entropy is…

Unusable thermal energy spread out throughout something. Highest for a gas because more micro states

Delta s = delta H/T Of cold and delta H/T of hot

In a vacuum…

There is no outside pressure, no exchange of heat, negligible work to expand balloon (if there is work it generates heat which balances out Delta U, meaning no change in T), Boyle: pressure decreases by half, volume doubles. Lose the force on the balloon from particles on the outside

ISOTHERMIC bc no particles to exchange temperature with

What happens to Maxwell Boltzmann at higher temp?

Goes right, spreads out thinner

POSITIVE work means…

work done TO a system, contraction

NEGATIVE work means…

work done BY system, expansion

there is a force that causes pressure from collisions with gas particles because…

there is an impulse or change in momentum, which can only occur with force

When transfering hot to cold, particles with ____

highest KE are transferred most frequently to areas with lower AKE

3 forms of heat transfer

radiation, convection, conduction

In PHYSICS, work is from the perspective of

the system itself

Formula for entropy

delta Q/delta T

1st Law of Thermo

conservation of energy, Delta U = Q+W

Second Law of Thermo

the universe always has positive gain in entropy

processes such as thermal equilibrium are…

irreverisble and lead to an increase in entropy IF considering the ENTIRE system

if there are higher temperatures, then entropy will have

less change

Types of Pressure

Absolute Pressure = Patm+Pgauge. Absolute is the one to use for PV=nRT

absolute pressure uses absolute zero as its zero point, while gauge pressure uses atmospheric pressure as its zero point.

If theres no change in V,

theres no work

if piston is free moving

pressure is constant

Gauge pressure is 0 when…

the gas is at the atmosphere’s pressure (since gauge pressure is additional pressure due to fluid)

in rate of heat flow… ___ doesn’t matter

moles and size of gas molecules

How to view forces at angles/corners of a shape

Look at distance as d√2 NOT F√2

which way do fields go and where does a negative go in a field?

Away from positive, towards negative. Electrons move AGAINST field

Charge

Remember NEGATIVE or positive, if its in e or C and nano or micro

Electric field lines point toward more/less potential

LESS potential, closer to negative has less potential (more neg)

How to find KE of a particle in system

Conservation of Energy: Delta K = NEGATIVE Delta U

How to find distance or velocity of a particle in system

Conservation of ENERGY

remember mass, mass of electron is much less so it has more ACCELERATION and thus velocity than proton

Moving positives together….

Requires the input of work into the system, increases potential because positive charge and closer distance

The magnitude of an E field of a single particle…

has the SAME magnitude and SAME direction on ALL other particles, regardless of the other particles’ sign of charge or magnitude of charge.

Think of it like F=mg, mass does not affect g

Closer to a negative charge has more/less potential

LESS, more negative

E-field in capacitor

UNIFORM (exception is end points)

Do NOT treat the field the same as a sphere using the Coulomb Law-derived equation

Definition of Capacitance

Amount of voltage/potential stored in a capacitor per a certain distance.

Capacitance has its own PE designated as U_c

As distance of the capacitor plates get _____ and as area _____, the U_c/C increases

smaller, increases

Keeping a capacitor plugged in to a battery maintains

constant voltage

Removing a capacitor plugged in to a battery maintains

constant charge

What impacts Capacitance?

The physical properties of the plates, such as area, distance, material (dielectric constant or presence of dielectric)

Capacitance is dependent on _____

charge

IN a capacitor, electric field is dependent on

the strength of flux lines, or CHARGE

If a position has MORE potential energy, then that state is…

LESS favorable, has MORE V

More PE for negative charges means…

HIGHER V

Relationship between V and U_e

Can have OPPOSITE signs bc it depends on sign of charge

which particle has the highest potential?

Positive

How to find total V or PE of a system

SCALAR addition, NOT vector

Charge inside a conductor

NONE, all on surface

In conduction, the potential difference afterwards is…

0, both have same potential

If there’s no delta V, then there’s no

No Delta U_e, no E and no FE (like having only constant velocity and no acceleration)

How to find field from equipotential lines

perpendicular, towards lower potential

How does distance impact voltage?

NOT constant distance per change in voltage, exponential change according to 1/r

Moving perpendicular to a field

does NOT change V

A system defined as a SINGLE particle

has NO PE on its own

A positive charge attracts

a negative AND a neutral

Difference between insulator and conductor

insulator only gets polarized as atomic level, conductor gets polarized on large scale because electrons can move around

Electric Permitivity (ε)

degree to which a material can be polarized

Electroscope

leaves outward means charged, could be positive or negative

Charge by Induction

NOT touching. Gives the material OPPOSITE charge if connected to ground wire, but nothing if not touched only temporary polarization. Ground not rod HAS to be removed first.

Triboelectric effect

rubbing/friction moving electrons, higher affinity (ε) takes electrons

Conduction

charges split, equal charge density

ρ

charge density, could be of surface area or volume, Q/A or Q/V

Kirchoff’s Junction Rule

Conservation of charge

Electric Flux (Φ)

E∆A, density of field/lines

What is Φ in between two like charges?

0, asymptotic

How to find strength of E in system

VECTOR not scalar addition

If there’s a charge

then there’s also a FIELD

*****For work, remember that

only the one component matters bc work is qEd*cosØ

If you are moving a charge in its normal direction, the field is doing or getting work done?

DOING

How does the potential of a sphere compare at different parts?

the V of sphere is SAME throughout, different as you get outside of it

The potential line of a field is VERTICAL/striaght when

it is going directly from a positive to negative, i.e. equipotential lines of capacitor

Which formula has a radius squared?

F and E, NOT V or U

Work moving inside a sphere

ZERO, equipotential and NO FIELD inside

When you are finding the potential away from a sphere, you do NOT have to add

the distance from the center bc same everywhere in sphere

How does a dielectric work?

The dielectric is typically an insulator that gets polarized and weakens the electric field because it creates an opposite field when polarized. This allows for the capacitor to store more charge. This reduces voltage and increase capacitance, thus meaning charge has to increase

Unit for Capacitance

F (farad)

How to find how much distance a particle travels before hitting a plate when sent through capacitor

Calculate force, F=ma, kinematics to find t, t*v = distance traveled

if capacitance and voltage increase, how does this impact Uc?

Increases from both according to Uc = 1/2C(deltaV)^2

How to find distance of added charge between two other charges

treat distance as (r-d) and other as d in Fe formulas

If a charge is on an angle from another charge…

then take that distance and plug it into force formula. THEN take components. Distance on a diagonal is MORE than straight component so LESS force. Remember DIRECTION of each force

What force dominates at the following levels? Microscopic, macroscopic, planetary/universal size

strong, electrostatic, gravity

How can a capacitor transfer charge in a circuit?

Induction only, no conduction or electrons “jumping” across gap

At what point of a charge do you measure its force?

From the CENTER, unless its a conducting sphere, then the OUTSIDE

When finding the net electric field or force, what should you be careful with?

VECTOR ADDITION DIRECTION

How to find spot where field is greatest from equipotentials

point where lines are closest together NOT closest to charge

motion of proton in capacitor

accelerates toward neg plate at CONSTANT rate

internal energy of a capacitor is equal to

Uc= QV = 1/2CV²

Every FRQ you must remember…

Units, show all work, use formulas, label

Experimental design show replication, use slope of graph and explain what is represents