Physics Flashcards
Nano (n) stands for
10-9
Pico (p) stands for
10-12
Micro (u) stands for
10-6
milli (m) stands for
10-3
centi (c) stands for
10-2
kilo (k) stands for
103
mega (M) stands for
106
giga (G) stands for
109
Name the five equations from “The Big Five” in regards to uniform acceleration?
- d = 1/2(V0+V)t
- V = V0 +at
d = V0t + 1/2at2
d = Vt - 1/2at2
V2=V02 + 2ad
What is gravity’s acceleration?
10m/s2
Formula for weight
w=mg
w= weight
g= gravity acceleration
What is the formula for Newton’s Law of Gravitation?
Fgrav= G (Mm)/(r2)
what is the formula for finding gravitational acceleration, g?
g = G (M/r2)
What is formula for velocity (V)?
V = d/t
What is formula for acceleration (a)?
a = V/t
What is Newton’s first law?
An object at rest will stay at rest, an object in motion will stay in motion
What is Newton’s second law?
F=ma
What is Newton’s third law?
For every action, there is an equal and opposite reaction
F1 on 2 = -F2 on 1
Friction Force = ?
Ff = µkFN
Friction force max =?
Ffmax= µsFN
Force parallel to inclined plane =?
mgsinΘ
Force perpendicular to inclined plane = ?
mgcosΘ
What is the equation for finding the center of mass for point masses?
Xcm = m1x1 + m2x2…./m1 + m2…
What is the equation for finding the center of gravity?
Xcg = w1x1 + w2x2…../w1 + w2…
acceleration of uniform circular motion =?
ac=v2/r
What is the formula for finding force of circular motion?
Fc=mac=mv2/r
Ƭ, torque =?
Ƭ = rFsinΘ
Define torque
torque is a measure of a force’s effectivness at making an object spin or rotate (accelerate rotationally)
What is rotational inertia?
Resistance to rotational acceleration
Which is easier to rotate: Weights very close together at the center of mass, or weights very far apart?
Close together
F=ma, how does this apply to torque and inertia?
Ƭnet= Iα
I is rotational inertia
alpha is rotational acceleration
Describe how the rotational axis affects the rotational inertia
The inertia will be smallest when the rotation axis passes through the objects center of mass
Which has smaller rotational inertia: solid ball or hollow ball
Solid ball - therefore it would roll more easily than the hollow ball
W (work) =?
W=Fd
P (power)=?
P = W/t
work/time
KE=?
1/2mV2
Total work =?
change in KE
PE=
mgh (if height increases)
-mgh (if height decreases)
E=
E= KE + PE
Conservation of total mechanical E equation
KE + PE = KE2 + PE2
What happens to PE and KE when there is friction?
total mechanical E is not conserved.
KE + PE + Wby F= KE2 + PE2
MA (mechanical advantage) =
MA = deffort/dresistance
Describe the difference in lifint a block 2 m and pushing it up a ramp 2m in height
The ramp takes less force but the work ends up being the same
Efficiency =?
Woutput/Einput
What is unit for F
N
What is unit for W?
J
What are the three ways energy can be transferred? Describe
Conduction - direct transfer of E (touching the hot stove)
Convection - E transferred like a fluid (candle warming air)
Radiation - Absorption of E via light waves (sun warming)
What is symbol for momentum?
p
What is unit for momentum? (p)
kg • m/s
Is momentum a vector?
Yes - it includes direction!
p=
p=mv
(momentum)
What is symbol for impulse?
J
What is unit for impulse? (J)
N • s
(second)
J=?
Δp=Δmv=FΔt
Momentum is conserved within a system. What equation describes this?
m1V1 + m2V2 = m1V1’+ m2V2’
What are the three kinds of collisions? Describe them
- elastic - total momental & total KE conserved
- Inelastic - total momentum conserved NOT total KE
- Perfectly inelastic: obejcts stick together afterwards. momentum is conserved.
Elastic collision is the only one KE is conserved in
Ball 1 and Ball 2 roll toward each other at the same speed, 5 m/s. Ball 1 = 8kg, Ball 2=2 kg. After collision, they stick together. What is new velocity after collision?
3 m/s
8kg * 5m/s + 2kg * -5 m/s = 10kg *?
What is the symbol for angular momentum?
L
Angular momentum (L) =?
L = lmv = Iw
(el)mv (eye)w
Just multiply linear momentum by length (p=mv)
The greater the change in momentum, the _____________ the impulse required
greater
J = Δp
Angular momentum =?
L=lmv = Iw
l (el) is lever arm, m is mass, v is velocity
I(eye) is moment of inertia, w is angular velocity
L is angular momentum
What is law of conservation of angular momentum?
Formula?
If net torque is 0, then total angular momentum doesn’t change
Li=Lf
Iiwi=Ifwf
What happens to moment of inertia and angular velocity when a sprinning ice skater pulls her arms closer to her body?
She pulls her arms closer to the axis of rotation, so her moment of inertia decreases and her angular velocity increases (she spins faster)
What is symbol for density?
p (but the p has a tail)
What is units for density?
kg/m3 or g/cm3
p (density) = ?
m/V
What is the density of liquid water?
1000 kg/m3 or 1 g/cm3
What is specific gravity? Formula?
How dense something is compared to water
Specific gravity = p/ph2o
If a graph plots position versus time, what does the slope =?
velocity
If a graph plots velocity vs. time, what does the slope =?
acceleration
What does the area under a graph = when plotting velocity vs. time?
d
A newton (N) =?
kg•m/s2
torque =?
(I)(alpha)
torque = rotational inertia * rotational acceleration
The farther awa the mass is from the axis of rotation, the _____ rotational inertia will be
greater
Does having a great amount of inertia mean it is difficult to rotate or easy to rotate?
difficult
Is rotational inertia greater when it passes through the objects center of mass or through its side?
Side, inertia is smallest when passing through center of mass
torque =? (in relation to r and F)
torque = rFsinØ
if torque is perpendicular to r, then torque=rf
Which rolls more easily? Solid ball or hollow ball? why?
Solid ball, because it has smaller rotational inertia, the rotation axis passes through the center of mass
Is work a vector or scalar?
scalar, it has no direction
What is the unit for work?
J (Joule)
1 J (joule) =?
N*m
W=?
W=Fd
(force * distance)
What is the definition of power?
How fast work gets done
1 watt=?
1J/s
Power (P)=?
P = W/t
work/time
P=Fv
KE=?
1/2mv2
Total mechanical E =?
KE + PE
equation for conservation of mechanical energy:
KE + PE = KEf + PEf
unit of momentum (p)
kg*m/s
is momentum a vector or scalar?
vector
p(momentum)=?
p=mv
J respresents what?
Impulse
J=?
J=►p=►mv=F►t
Law of Conservation of Total Angular Momentum
Li=Lf = Iiwi = Ifwf
(initial momentum = final momentum)
(Initial rotational inetial * initial angular velocity = finals)
is pressure a vector or scalar?
scalar
FB=?
(buoyant force)
FB=pVg
(density*volume that’s submerged*gravity)
Pascal’s Law formula
F1/A1=F2/A2
What is the surface tension of water?
.7 N/m
flow rate (fluid) =?
f=Av
area*velocity
A1V1=?
A2V2
Bernoullis equation? (ideal fluid)
P1 + 1/2pv12 + pgy1= P2 + 1/2pv22 + pgy2
p is density of flowing fluid
v is velocity
y is height above horizoantl reference
P is pressure
How fast does a liquid exit a hole? (equation)
Vefflux= Í2gD
(square root of )
D = y1-y2
Stress=? (opposed to pressure)
F/A
force/area
(the difference between pressure is pressure must be perpendicular to the object it acts on)
tensile or compressive strain =?
►L/L0
tensile/ compressive strain is stretching or squeezing
Shear Strain =?
x/L0
shear strain is bending
x=distance of shear/bend
Hooke’s law?
stress = modulus x strain
(modulus is a constant)
F=kX
Young’s modulus?
tensile and compressive stress
►L = FL0/EA
(FLEA!)
(E is modulus, unit is pascal)
The lower the modulus the ______ it stretches
more
Shear modulus =?
(bending!)
X= FL0/AG
(FLAG!!)
G is modulus
elementary charge =?
electric charge of proton or neutron
1.6 x10-19 C
Formula stating that electric charge is always conserved?
q = n(+- e)
What is avagadro’s number?
6.02*1023
FE=?
(electric force)
k q1+q2/r2
k is proportionality constant, usually = 9*109 N*m2/C2
Electric field vectors point _____ positive source charge and _______ negative source charge
away
toward
EbyQ = ?
(electric field energy)
k Q/r2
Fon q =?
F = qE
q is the charge that feels the field
E is in N/C
Ø =?
(electric potential)
V = k Q/r
Ø unit is volt!!
for electric potential:
►KE = -►PE
Postive charge (proton) increase KE when they move toward point of ____________
lower Potential
negative charge ( electron) increase KE when they move toward point of ______________
higher potential
Define current
net movement of charge
I =?
(I is current)
I = Q/t
units of current is c/s
A (ampere) =?
c/s
R=?
(R is resistance)
R= V/I = p L/A
(voltange/resulting current)
p is resistivity which is intrinsic resistance
L is length
A is cross sectional area
What is the unit of resistance?
ohms
Resistors in series
in parallel?
series: R = R1 + R2..
parallel: R1R2/R1 + R2
What are capacitors?
Pair of conductors that can hold equal but opposite charge
Q=?
(Charge on a capacitor)
Q=CV
C is a constant, capacitance, unit F ( farad)
What does capacitance measure?
the “capacity” for holding charge
PE=?
electrical PE stored in capacitor
PE = 1/2 QV
Q is charge on the capacitor
V is voltage
Resistors in series always ahve the same ______, resistors in parallel always have the same __________
current (I)
voltage
((in a book series, the main character (I) is the same)
P =?
power dissipated by the resistor (resistor gets hot!)
P=I2R
P=?
Power supplied to the batter
P=IV
What is the name of the thing that increases capacitance?
Dialetric, it is insulating material
If a charge moves parallel to magnetic field lines ____
it feels no force
FB=?
(magnetic force)
FB= q (v * B)
v is velocity of charge q
B is magnetic fieldc
sin90=?
1
a coil of wire is called a ?
What is inside of it?
solenoid
a magnetic field, parallel to central axis
What is Hooke’s Law for Springs?
F = -kx
F is force exerted by spring
k is constant. the greater it is, the stiffer the spring
x is string’s displacement
T respresent?
period, time it takes to complete one cycle (spring)
f =?
Frequency
f = 1/T
T is period ( in seconds)
*******
v =?
Wave speed
v = wavelength * frequency
f is constant - see big rules. wave speed is dependent on wavelength
MCAT LOVES WAVES
What is Big Rule #1 for waves?
*********
The speed of a wave is determined by the type of wave and the characteristics of the medium NOT by the frequency
What is Big Rule #2 for waves?
*******
When a wave passes into another medium, its speed changes but its frequency does not
What does amplitude mean for waves?
How much E the wave transports. It has nothing to do with anything else
Distance between two nodes (L) =?
1/2wavelength
What does sound travel fastest through? Slowest?
Fastest through solids, then liquids, then gases
What is intensity? (sound waves)
energy the sound wave transmits per second (power) per unit second, it is w/m2
w is watt
What is intensity level?
The sound level.
The Doppler Effect equation
fD=fs v+-vD/v-+vs
fD is frequency heard by detector
fs is frequency emitted by source
v is speed of wave
vd is speed the detector is moving
vs is speed source is moving
f =?
focal length
f = 1/2 r
what is the mirror and lens equation?
1/o + 1/i = 1/f
o is object’s distance from the mirror (ALWAYS positive)
i is image’s distance from the mirror
f is focal length of mirror
with mirror and lenses, if both f and i are positive, then image is _____
on the same side as the human observer (but in lens oppostie sides)
with mirror, if i is positive, image is ____
if i is negative, image behind mirror is _____
real
virtual
m =?
m is magnification factor
if m is positive _____
if m is negative ______
m = -i/o
m + then image is upright
m - then image is inverted
P =?
lens power
P = 1/f
f is focal length in meters
power unit is diopeter
hyperopia is
farsightedness (can’t focus near)
what lens is used to correct myopia?
diverging
myopia is
near sightedness (can’t focus far away)
what lens is used to correct hyperopia?
converging
When a ball in projectile motion is launched, it does not accelerate: horizontally or vertically?
horizontally
Velocity is the same at every point in projectile motion, once the ball is launched, for?
horizontal
Equation for displacement for horizontal motion
x=v0t
Equation for velocity for horizontal motion
vx=vox
equation for acceleration for horizontal motion
ax=0
Name equation for displacement for vertical motion
y=v0t + 1/2(-g)t2
name equation for velocity for verticle motion
vy=v0y + (-g)t
name equation for acceleration for verticle motion
ay=-g
Newton’s law of gravitation equation
Fgrav=G Mm/r2
according to newton’s law of gravitation: the magnitude of gravitational force is ______ proportional to the square of the distance b/w the centers of the object
inversely
What will happen to the gravitational F b/w two objects if the distance between them is doubled?
Fgrav=G Mm/r2
If distances is doubled, then r increases by factor of 2, and Fgrav will decrease by factor of 22 = 4
What will happen to the gravitational force between 2 objects if the distance is cut in half?
If distance is cut in half, then r decreases by factor of 2 and Fgrav wil increase by factor of 22 = 4.
Fgrav=G Mm/r2
equation for gravitational acceleration?
g=GM/r2
g depends on radius and mass
M is mass
r is radius
G is universal constant
Compare and contrast coefficient of kinetic friction (uk) vs coefficient of static friction (us)
Kinetic:
experimentaly determined
+ number with no units
the greater the number, the greater the force of kinetic friction
Static:
There’s a max between 2 surfaces
it is always larger than coefficient of kinetic friction
can only compute its max force (Ffmax=usFN)
Draw an example force diagram with F parallel F perpendicular, FN, Ff
of a block sliding down a ramp
A block of mass m=4kg is placed at the top of a frictionless ramp of incline 30 degrees and length 10m. What is the block’s a down the ramp? How long will it take for the block to slide to the bottom?
a = 5m/s2
t=2s
See green star page for how to calculate
A block of mass m slides down a ramp of incline angle 60 degrees. If the coefficient of kinetic friction b/w the block and surface of the ramp is .2, what is the blocks acceleration down the ramp?
7.5m/s2
See green star page for how to do
what is the formula for uniform (centripetal) acceleration?
ac= v2/r
Torquenet=?
Ia
I = rotational inertia
a = rotational acceleration
Like F=ma! I is like mass, a is accerleration
Define gravitational local, spring, and gravitational genearl PE (the equations)
a. gravitational, local (PE = mgh)
b. spring (PE = kx2
/2)
c. gravitational, general (PE = –GmM/r)
In regards to torque, if it is spining counterclockwise it is____ vs. if it is spinning clockwise (positive or negative)
if CCW +
if CW -
If torque a force?
No, it is a property of a force, it is a mesasure of the effectivness of a force at making an object spin or rotate.
Is speed constant in uniform circular motion? is velocity constant?
Yes, speed is constant. But, velocity is a vector - so it keeps changing b/c it is going in a circle, therefore it is undergoing acceleration
If a force acts at the pivot or along a lilne through th epivot, then it’s torque =?
0
if we are given lever arm and force, how do they relate to torque?
torque = lF
(lever arm and force)
contrast translational and rotational equilibrium
translational - forces cancel (Fnet = 0)
rotational - torques cancel (torquenet= 0)
Work done by kinetic friction depends on ______
path taken (in contrast to “normal work” where direction doesnt matter, as its scalar
What are the properties of an ideal fluid?
incompressible, neglible viscosity (syrup is very viscous), flow is laminar (aka flows smoothly), flow rate is steady
Is the modulus for glass or rubber greater?
modulus is greater for glass - the lower the modulus the more it stretches
If FE is positive, particles _______
repel each other
If FE is negative, particles ______
attract each other
If E (electric field) is positive, then Q is? If E is negative, then Q is?
E+ then Q+
E- then Q-
Electric field diagrams indicate the direction of the electric force that a ______ would feel if it were placed in the field
positve test charge
What is an electric dipole?
pair of equal but opposite charges
In electric potential, we think of the electrif field as a ? (vector or scalar)
scalar - no direction. This helps us understand it in relation to energy, work, and speed.
What is the unit for current (I) ?
c/s or A (amp)
What causes current?
voltage
What is voltage?
a potential difference
voltages that create currents are called?
emf (electromotive force)
What are the properties and formula of Ohm’s Law?
V=IR
Resistance is constant, voltage is varried, current reverses direction if polarity of voltage is reversed
Draw a DC circuit
Direcrion direcion of current is toward negative terminal. It is the direction positive charge carriers would flow (even though what is actually happening is electrons are drifing towards higher potential (+)
If there are three light bulbs in parallel and the middle burns out, what happens to the intensity, current, and power?
intensity of the other two stays the same. total current decreases. power supplied by battery will decrease. battery will last longer
C = ?
C is capacitance
C = E0 A/d
Eo is fundamental constant of nature, permittivity of free space =8.85x 10-12 F/m
This measures the capacitator’s plates capacity of holding charge at a certain voltage
Why use a capacitor?
To create a uniform electric field, and to store electircal PE
Ed’s formula
V=Ed
explains that electric field b/w capacitance plates is same at every point
E is electric field
C =?
in the presence of a dialectric
(capacitance)
C=KE0 A/d
K is dialectric constant. In a vacuum, this =1.
If a dielectric is placed between a disconnected & charged capacitor, what happens to Q, C, V, PE, and E?
Q remains the same - charge cannot change if not connected to battery.
C increases - therefore V decreases (Q=CV)
E (electric field) decreases (V=Ed
PE decreases by factor of K (PE = 1/2QV)
If dielectric is inserted while connected to the battery, what happens to C, Q, V, E and PE?
E-Einduced = E/K
Remember, K is dialectric constant
C=KE0 A/d
C increases by factor of K
Q increases by factor of K
V stays the same
E stays the same (V=ED)
PE increases by factor of K (PE = 1/2 QV)
What is E induced in relation to dielectrics?
Dielectric polarizes molecules, creating induced charge on surface of the plates, creating a new electric field (E induced) in the opposite direction of the dielectric, leads to a decreaes in total electric field
Draw and describe DC vs AC circuit
Vrms=?
rms is root mean square, means average.
Vmax/ς2
(Vrms equals max voltage over square root of two)
Irms=?
Imax/ς2
max current over square root of two
What is a magnetic field created by?
Moving electric charges
A magnetic field exerts a force on ______ but not on ________
exerts force on charge that is moving through the field, but not on a charge at rest
- vs. x
out of the page into the page
Can magnetic forces do work?
NO. KE is constant. they cannot change speed of a particle, only direction of a particle.
Explain L.H and R.H rule
if q is positive use RH
if q is negative, use LF
Thumb points i direction of velocity, fingers in direction of B. direction of FB will be perpendicular to palm
If current is counterclockwise, B points _________ inside the loop and _______ outside the loop
out of the page inside the loop and into the page outside the loop
If current is clockwise, B points ______ inside the loop and ____ outside the loop
into the page inside the loop and out of the page outisde the loop
If solenoid has many windings and the length is much greater than the diameter, then the magnetic field is?
Almost uniform and is proportional the current and to the number of turns per unit length (N/L)
Draw example magnet diagram
In Hooke’s Law, the greter K is, the ______ the spring is
The greater K is, the stronger the spring is
What is restoring force?
The force the spring provides because it is always trying to get back to equilibrium
What is the unit for frequency?
Hertz (Hz)
cycles/sercond
f=?
(frequency)
f= 1/T
f=1/(2π)ς(k/m)
f= 1/(2π)ς(g/l)
last one is for pendulums
T =?
(three equations)
(period)
T= 1/
T = 2π ς(m/k)
T= 2π ς(l/g)
last one is for pendulums
Draw first harmonic, second harmonic, and third harmonic. Give equations for each
First: L=1(1/2§)
§=2L/1
Second: L=2(1/2§)
§=2L/2
Third: 3(1/2§)
§=2L/3
Therefore, §=2L/n (n is the harmonic #)
§ is wavelength
What is equation for standing wave frequency for 2 fixed ends?
fn=(n/2L)v
n is 1,2,3, etc
Are sound waves transerse or longitudinal?
longitudinal, direction the medium particles oscillate is parllel to the direction the wave travels.
The speed of sound waves depend on what?
medium’s resistnace to compression and density
sound waves
the greater the medium’s resistance to compression:
the faster sound travels
sound waves
The greater the medium’s density is:
the slower sound travels
What is intensity? What is the unit?
Enegy the sound wave transmits per second (power) per unit area
w/m2
w is waatts
What is intensity level measured in?
decibels! dB
or bel (B)
B =?
B is intensity level. tail on B.
B = 10log10(I/I0)
If I is multiplied by 10, add 10 to B
If I is divided by 10, subtract 10 from B
Ex: If I is multiplied by 10,000, add 10+10+10+10=40 to B
The speed of light =?
3 x10 8 m/s
Compare wavenlength and frequency of visible light
ROYGBV
Red has lowest frequency therefore longest wavelength
Violet has highest frequency, therefore shortest wavelength
speed of light =? (formula)
c = fς
(fequency * wavelenth)
When EM (electromagnetic) waves travel through a vacuum, they travel ___
at the same speed
E=?
E is photon energy
E=hf=h c/ς
h is plank’s constnt, will be given on mcat
What does the law of reflection say?
The angle of reflection is equal to the angle of incidence (see notes to draw)
What is refraction
Bending as light hits water (or some other medium)
When does the incident ray angle = the refracted ray angle?
When incident ray is perpendiuclar to the surface
What is index of refraction?
How fast light travels through a medium
What is the symbol for index of refraction?
n
equation for index of refraction
n=?
n = c/v
speed of light in vacuum/speed of light in medium
The greater n is (index of refraction), the ______ light travels through a vacuum
slower
Law of refraction formula (shell’s law)
n1sinØ1=n2sinØ2
If n2 > n1, then the ray will bend toward the normal
if n2<n1>
</n1>
What is total internal reflection?
what happens when a light ray travels from a medium of high refractive index into one of lower, and if the ray’s angle of incidence exceeds the criticle one
What is the exception to big rule 1 with light waves?
when light travels through a material, different frequencies have different speeds (this is why we have diff. colors). Diff colors have different refractie indexes - different angles of refraction
in concave mirror, f is
+
in convex mirror, f is
-
Draw the focal points and c for concave and convex mirrors
what does c represent in mirrors?
center of curvature
convex mirrors can only create
virtual images
real image vs. virtual
real: light rays actually focus @position of the image and can b eprojected on a surface
virtual, light rays dont actually focus on apparant location of the image, cannot be projected
lens with short focal length refracts ________ than lens with longer focal lenth. shorter focal length also has ______
more light
greater power
P =?
lens power
P = 1/f
What determines the brightness of a lightbulb?
Power. P = I2R
So current is the biggest factor in the brightness of a lightbulb. The current will go towards path of least resistance, so if it has low resistance, it has stronger current, more power, and brighter lightbulb
Electrical PE (U) =?
U = k q1q2/r = U = 1/2qV
(charge * voltage)
A magnetic force can accelerate a charged particle by:
changing direction of particle. It cannot change the magnitude of its velocity
Equation describing a charged particle’s motion in a uniform magnetic field
R =
R = mv/qB
R is radius, v is velocity, q charge, B magnetic field, m mass
Capacitors in series have the same?
Capacitors in parallel have the same?
I (current)
voltage
How is charge stored on the capacitor?
Evenly distributed on the surface
Power consumed by a capacitor equation
P =?
P = 1/2 qV
Volume is directly correlated to what in waves?
Amplitude
Waves completely out of phase create what kind of interference?
Destructive
If wavelength decreases in light waves, the angle of separation would ________
decrease. they would move closer together
Equation for power consumed by a capacitor
P = 1/2qV
