Concepts to memorize Flashcards | Knowt (2024)

A x B = C

Thumb = A, fingers = B, palm = C

Fg = Gm1m2/r²

• G = 6.67 × 10^-11 Nm²/kg²

0 <= fs <= usN (max)

• us = coefficient of friction

• N = force that is perpendicular to the plane of contact

• Fs is not constant

Fk = ukN

• Fk is constant

• Us > uk; maximum value of static friction is always greater than constant value of uk

Fg = mg

G = 10 m/s²

Fnet = ma = 0

• unless outside force is applied

Fab = -Fab

• there is always an opposed but equal action

V = v0 + at

X = v0t + at²/2

V² = v0² + 2ax

X = vt

• Will only experience motion in the y direction

  • Find separate vy and vx

Force causes an object to move without any rotation

• all forces added together = zero

Rotational motion

T = r x F = rFsintheta

• R = length

• F = magnitude

Equilibrium = vector sum of all torques acting on an object = 0

K = 1/2mv²

• J = kgm²/s²

U = ½ kx²

• where x is the magnitude of displacement from the equilibrium

Expansion: system is pushing on surroundings, positive work

Compression: surroundings are pushing on the system, negative work

Isovolumetric/isochoric: no work done because no change in volume

isobaric: W = PchangeV

P = W/t = changeinE/t

• W = J/s

Efficiency = Wout/Win = (load)(load distance)/(effort)(effort distance)

• Load = weight

• Effort distance = displacement x number of pulleys

• Effort = half the force

L = al (triangle) t

• length changes = a lot

Change in V = beta V (change in t)

• beta = 3a

Water = 1 cal/gK

Q = mcdeltaT

Heat is constant as phase changes are changes in potential energy

• Q = mL

Isothermal: Q = W

Adiabatic: W = -U

Isobaric: multiple

Isovolumetric: Q = U

Pnet = Fnet/A

• 1 Pa = 1 N/m²

P = P0 + densitygz

• P = pressure at surface

• Z = depth of object

Pgauge = P - P atm = (P0 + densitygh) - P atm

• if p0 and patm are equal, the Pgauge = densitygh

P = F1/A1 = F2/A2

• V = A1d1

• W = PchangeinV (isobaric — constant pressure)

• N = Kgm/s²

Fbuoy = densityVdisplacedg = densityVsubmergedg

• V = volume

Q = flow rate

P = pressure gradient

Vc = Nr viscosity / density D

• Nr = reynolds number

Q = v1A1 = v2A2

• smaller cross sectional areas, liquids move faster

• systems at higher pressure have higher energy density

p1 + pgh + ½ pv² = p2 …

• where pgh = potential energy

• 1/2pv² = kinetic

Fe = kq1q2/r²

• K = 8.99 × 10^9 Nm²/c²

U = kQq/r

• Electric potential = V = U/q

• V = kQ/r

Change in V = Vb - Va = Wab/q

• positive test charge will move from positive to negative

  • Decreases charge

• Negative test charge will move from negative to positive

  • Increases charge

In both cases, potential energy is decreasing

• V = kqd/r² cos theta

  • P = qd

    • P = dipole moment

  • therefore V = kp/r² cos theta

Electric potential at any point along the plane is 0

E field = ¼ pi e0 x p/r³

Unpaired electrons and permanent atomic magnetic dipoles

• strongly magnetized in the presence of an external magnetic field

B = u0 I / 2pi r

• R = perpendicular distance

• U0 = permeability of free space

Fb = qvB sin theta

• charge must have perpendicular component of velocity

Thumb = direction of velocity vector

Fingers = direction of magnetic field lines

Palm = direction of force vector for positive

Back of hand = direction of force change for negative

Fb = ILBsintheta

• current = flow of positive charge —> also use second right hand rule/current = thumb

• metal atoms can easily lose one or more electrons —> good conductors

• Electrolytic: no ionic solutions are always less conductive than ionic solutions

I = Q/change in t

• Measured in A = C/s

V = IR

• V = e (cell) - I r(int)

  • R = internal resistance

P = W/t = changeinE/t

• P = IV = I²R = V²/R

Series:

Vs = V1 + V2

Rs = R1 + R2

Parallel:

Vp = V1 = V2

Rp = 1/R1 + 1/R2

C = Q/V

• Farad: F = C/V

• Q = charge

C = e0 (A/d)

• e0 = 8.85 × 10^-12 F/m

E = V/d

• direction: positive to negative

C’ = kC

• Isolated: decreases the voltage, increasing capacitance

• Circuit: voltage stays the same, increases the capacitance from an increase in stored charges

Series: 1/Cs = 1/C1 + 1/C2

Parallel: Cp = C1 + C2 +…

Measures a change in voltage

• since placed in parallel; infinite resistance ideal

Calculates resistance

• does not require a current

T = 1/f

• number of cycles per seconds

• f = 1/T: number of seconds in a cycle

At rest: nodes

Midway between the nodes: antinodes

V = sqr(B/density)

• B = bulk modulus, measure of resistance to compression

• Sound travels fastest through solid and slowest through a gas

Signage depends on the numerator/denominator

• If source is moving towards the observer: frequency is increasing; therefore negative

• If source is moving away from observer: frequency is decreasing; therefore positive

I = P/A

• I = P/4pi r²

B = 10log(10) I/Io

• Io is the threshold of hearing (1 10^-12 W/m²)

Wavelength = 2L/n

F = nv/2L

• Lowest frequency/longest wavelength = first harmonic

• Number of antinodes = harmonic

Same formula as strings

• If pipe is open on both sides, there is an antinodes on both sides

• Number of nodes = harmonic

Always an odd number of harmonics

• wavelength = 4L/n

• F = nv/4L

Count the number of quarter wavelengths

Real or virtual

• Plane mirrors are always virtual. Focal distances = infinite

Concave mirrors/convex lens:

• MUV in front —> object in front of focal lens is magnified, upright, virtual

• Behind the RIM —> object behind the focal lens is real, inverted, and magnified

Convex mirrors/concave lens: always reduced, upright and virtual

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