physics info i need to learn

kirchhoff’s junction rule

Ienter = Iexit

in a circuit total current entering a junction equals the current exiting it

Ohm’s law equation

V = IR

V= voltage

I= current

R= Resistance

kirchhoff’s loop rule

V = V1+V2+V3+….. = 0

Sum of the voltage drops around any closed loop in a circuit equals 0

unit for current

Ampere(A)

unit for resistance

Ohms

unit for voltage

volts(V)

what is a Pa(pascal) equal to

N/m²

hydrostatic pressure equation

hydrostatic pressure is the pressure exerted by the weight of a fluid

P = ρgh

ρ = density of fluid

g= 10m/s²(gravity acceleration

h= height

partial pressure equation

Pgas = Xgas+Ptotal

Xgas = mole fraction of the gass

Ptotal = total pressure

upward buoyant force and weight of the fluid relationship

buoyant force = W

Weight equation

W = mg

m = mass

g= 10m/s²(gravitational acceleration)

what is the doppler effect

observed frequency changes relative to motion

Ex. When an ambulance is stationary the frequency of its siren’s sound waves is stable to the observer

As the ambulance starts moving and gets closer to the observer they will notice that the frequency of the siren’s sound wave increases

wavelength and frequency relationship

they have inverse relationship

what is refraction

bending of light occurring at the boundary between 2 different mediums with different values of n

index of refraction(n) equation

n = speed of light in a vacuum( c ) / speed of light in a medium(v)

what is an incident angle

angle between the axis perpendicular to the surface and the ray

what happens when the incident angle increases

light is refracted closer to the surface

what occurs when a critical angle is formed

light is refracted at 90 degree angle and continues parallel to the surface

when does total internal reflection occur

when an incident angle is greater than the critical angle

ideal gas law equation

PV = nRT

P= pressure

V=volume

n= # of moles

R= 0.08 L x atm/mol x K

T= temp in kelvin

wave velocity equation

v = λf

λ = wavelength

f = frequency

for a standing wave how is the λ(wavelength) calculated

length of the string(L) and number of antinodes/nodes(n)

λ = 2L/n

what is snell’s law of light refraction

n1 sin θ1 = n2 sin θ2

n1 = refractive index of medium 1(ex. air)

n2= refractive index of medium 2(ex. glass)

Work(w) formula

W = F x d

F= force

d= distance

kinetic friction force equation

F_{f =} μ_k * F_N

μ_{k =} coefficient of kinetic friction

F_N = Normal force

on a horizontal surface what is the normal force equal to

F_N = mg

if a block slides down a ramp at constant velocity what happens to all the parallel forces

sum of all parallel forces is 0

Fparallel = F_w sin θ - F_k = 0

F_k = F_w sin θ

if a block slides down a ramp at constant velocity what happens to all the perpendicular forces

sum of all perpedicular forces is 0

Fperpendicular = F_N - F_W cos θ = 0

F_N = F_W cos θ

harmonic resonance frequency for standing wave on a string equation

f_n = nf₁

f₁ = frequency of standing wave with one antinode

what are antinodes and nodes in standing waves

what is resonance

it generates standing waves on a string fixed at both ends

when a block that has a temp 35 degrees is submerged in water that has a temp of 25 degrees suppose the q value of water is 210J what is the q value of the block

q value of the block will be -210J because the heat of the block will transfer to the water

upper limit static friction force equation

F_s = μ_s N

N= normal force

what is static friction

frictional force that prevents 2 surfaces from sliding

if forces that promote sliding exceed the upper limit of static friction what happens

sliding will occur

is the coefficient of kinetic friction always greater or lower than coefficient of static friction

coefficient of kinetic friction is always less than coefficient of static friction

newtons 2nd law of motion

F = ma

m= mass

a= acceleration

when velocity is positive and you need to calculate acceleration using kinetic friction equation, is F_k negative or positive

F_k is negative because friction acts in the opposite direction

on an incline what is the perpendicular component of the weight of an object

W cos θ

on an incline what is the perpendicular component of the weight of an object equal to

the normal force

Work equation

W_f = Fd

F = force

d= displacement

what is the pressure equation

P = F/A

Capacitance equation

C = Q / V

Q = quantity of stored charge

V= voltage

in a parallel place capacitor, what is the equation used when there is a dielectric between the parallel plates

C = k · C₀

k = dielectric constant

C₀ = Capacitance when there is nothing in between

in a parallel plate capacitor why is C proportional to area of the plates

As the area of the plates increase more charge can be stored on it(increase in Q value)

Resistance of a resistor equation

R = ρ · L/A

ρ = resistivity

L= length

A= area

how to add resistors that are in a series

R_eq = R1 + R2 + R3….

how to add resistors that are parallel

1/R_eq = 1/R1 + 1/R2 + 1/R3….

in a pulley system what is the weight of the large block resting on the surface equal to

Weight largeblock = F_N + T_y

F_N = Normal force of the large block

T_y = y component of the rope attached to large block

in a pulley a large block is resting on a surface what is its F_s equal to

F_s will be equal to the x component of the rope attached to the large block

when an object is at rest or moving at constant velocity how do you calculate tension of the object’s supporting rope

Tension of the object’s rope is equal to the weight of the object

hooke’s law

F_el = -kx

k= spring constant

x= displacement

when a force is applied to a spring whether it may be by extending the spring or compressing the spring, how will the elastic force of the spring behave

the spring will apply elastic force equal to the force that was applied to it but in the opposite direction

Ex. if a force of 5 N is applied

the elastic force of spring will be -5N

unit for Work

joules(J)

unit for force

Newtons(N)

Power equations

P = Work/time(s)

P= Energy/Time

unit for power

watts(W)

what is watt equal to

joule/second

what is a joule equal to

1 kg⋅m²⋅s⁻²

N · m

Pa ·m³

Watt · second

Coulomb · volt

Torque equation

torque = rFsin(θ)

r= distance between pivot point and location where force is applied

F=force

elastic potential energy

U_el = ½ kx²

k= spring constant

x= displacement

what is ampere equal to

1 coulomb/second

current equations

I = Q/t

I = V/R

Q = charge

V= voltage

R= resistance

decibel and intensity relationship

for every 10dB increase the intensity increases by a factor of 10

Ex. 10dB = 10¹ times more intense

20dB = 10² times more intense

how does the velocity of sound waves change in different mediums

velocity of sound waves is fastest in solids

velocity of sound waves is faster in liquids

velocity of sound waves is slowest in gases

when a sound wave enters a solid, liquid, or gas what happens to its intensity

intensity decreases

frequency of sound wave and pitch relationship

as the frequency increases the pitch increases

for a pipe that is open at both ends what is the L value equal to

L = wavelength / 2

for a pipe that is closed on one end and open on the other end what is the L value equal to

L = wavelength / 4

frequency equation

f = velocity / wavelength