Physics Equations Combined Flashcards

Question 1

Q

(1) (Equation) What is the equation of kinetic friction?

Answer

A

f_k= μ_k * N

f_k= kinetic friction
μ_k= coefficient of kinetic friction
N= normal force

Normal force= m*g or n= mass x gravity

Question 2

Q

(1) (Equation) What is the equation for the force of gravity (or weight)?

Answer

A

F_g= mg

F_g= weight of the object
m= mass of object
g= acceleration due to gravity, 9.8 m/s² which is usually rounded to 10 m/s²

Key concept: The center of mass of a uniform object is at the geometric center of the object (like a ball). However, keep in mind that most objects are not uniform (i.e. human, tennis racket, TV)

Question 3

Q

(1) (Equation) What is the equation of average acceleration?

Question 4

Q

(Equation) what is newton’s first law of inertia?

Answer

A

states that an object will remain at rest or move with a constant velocity if there is no net force on the object.

F_net=ma=0

F_net= the net force
m= the mass
a= acceleration

Question 5

Q

(1) (Equation) what is Newtons’ second law of acceleration?

Answer

A

States that any acceleration is the result of the sum of the forces acting on the object and its mass. In other words, an object of mass m will accelerate when the vector sum of the forces results in some non-zero resultant force vector

F_net=ma

F_net= the net force
m= the mass
a= acceleration

Question 6

Q

(1) (Equation) What is Newton’s third law of acceleration?

Answer

A

Newton’s third law states that any two objects interacting with one another experience equal and opposite forces as a result of their interaction. In other words, to every action, there is always an opposed but equal reaction

F_AB= -F_BA

Question 7

Q

(1) (Equation) What is the equation used to find position from velocity?

To find maximum height when something is thrown (no time):

Answer

A

∆x=v_ot+ (1/2) a t ²

v= final velocity (may be 0)
v_o= is the initial velocity
a= acceleration due to gravity, 9.8 m/s² which is usually rounded to 10 m/s²
x or y= distance

Question 8

Q

(1) (Equation) in inclined plane equations, what is the force that is parallel to the ramp?

What is the force that is perpendicular to the ramp?

Answer

A

F_g∥=mg sin⁡θ (force parallel to the ramp)
F_g⊥=mg cos⁡θ (force perpendicular to the ramp) (normal force)

F_g∥= the component of gravity parallel to the plane (oriented down
F_g⊥= component of gravity perpendicular to the plane
m= mass
g= acceleration due to gravity (9.8 m/s^2)
θ= angle of the incline

Question 9

Q

(1) (Equation) What is the equation of circular motion, or centripetal force?

Answer

A

F_c= magnitude of centripetal force
m= mass
v= speed
r= radius of the circular path

Question 10

Q

(1) (Equation) What is the gravitational force equation?

Or the gravitational force between two objects

Answer

A

It’s important to note that if one of the masses is triple, then the gravitational force will triple. If the distance changes, the force will change as an exponent of that distance change.

Question 11

Q

(2) (Equation) What is the equation for kinetic energy?

Answer

A

K= Kinetic energy (in Joule)
Joule= (kg×m²)/s²
m= mass (in kilograms!)
v= speed in meters per second

Also, KE=1/2 mv ²= W= F*d

Question 12

Q

(2) (Equation) What is the equation for gravitational potential energy?

Answer

A

U=mgh

U= potential energy(in Joule)
Joule= (kg×m^2)/s^2 

    m= mass in kilograms
g= acceleration due to gravity (9.8 m/s)
h= height of the object above the datum.

Question 13

Q

(2) (Equation) What is the equation for elastic potential energy?

Answer

A

U= potential energy
k= spring constant (a measure of the stiffness of the spring)
x= the magnitude of displacement from equilibrium

Question 14

Q

(2) (Equation) What is the equation for work? (like pushing or pulling something)

Answer

A

Work is a function of force and displacement

W= F *d = Fd cos Ө

all= Work=F*d= 1/2 m v ²= P∆V

W= work
F= magnitude of the applied force
d= distance of displacement
Ө= the angle between the applied force vector and the displacement vector

Question 15

Q

(2) (Equation) What is the equation for work? Like a piston?

Answer

A

W= P ∆V

W= work
P= pressure
∆V= volume

Key Concept: When work is done by a system (the gas expands), the work is said to be positive. When the work is done on a system (the gas compresses), the work is said to be negative. The MCAT will not expect you to calculate the integral of a P-V graph using calculus, but you are expected to be able to calculate the area under a straight line graph if necessary.

Question 16

Q

(2) (Equation) What is the equation for power?

In terms of work?

Answer

A

P= power
SI unit for power is Watt, which is equal to J/s
W= work (which is equal to ∆E, the change in energy)
t= time

Question 17

Q

(2) (Equation) What is the work-energy theorem, what what does it mean?

Answer

A

The work-energy theorem states that when net work is done on or by a system, the system’s kinetic energy will change by the same amount. In more general applications, the work done on or by a system can be transferred to other forms of energy as well.

W_net= ∆K = K_f- K_i

W_net= total energy completed
∆K= change in kinetic energy
K_f= final kinetic energy
K_i= initial kinetic energy

Question 18

Q

(2) (Equation): What is the equation for mechanical advantage?

Answer

A

Mechanical Advantage = F_out/F_in

F_out= force exerted on an object by a simple machine
F_in = force actually applied on the simple machine

Mechanical advantage is a ratio of the output force generated given a particular input force.
Efficiency is a ratio of the useful work performed by a system compared to the work performed on the system.

Question 19

Q

(2) (Equation) In mechanical advantage, what is the equation for efficiency?

Answer

A

Efficiency
W_out= load or load distance
W_in= effort or effort distance

Another way to think of this is efficiency= (Force x distance for the load being lifted or the object) / (Force x distance for the person pulling the object).

In this case, the distance is going to be less for the object, and more for the person pulling. However the force will be less for the person pulling, and more for the object.

Mechanical advantage is a ratio of the output force generated given a particular input force.
Efficiency is a ratio of the useful work performed by a system compared to the work performed on the system.

Question 20

Q

3 (Equation) What is the equation for length change based on a temperature of a solid?

Answer

A

∆L= αL∆T

∆L= change in length
α= coefficient of linear expansion (given)
L= original length
∆T= change in temperature

CHANGE A LOT

Question 21

Q

3 (Equation) What is the equation for volume change based on a temperature of a liquid?

Answer

A

∆V= αV∆T

∆L= change in length
α= coefficient of linear expansion (given)
L= original length
∆T= change in temperature

Question 22

Q

3 (Equation) What is the first law of thermodynamics?

Answer

A

∆U= Q-W

∆U= change in internal energy= positive: increase temperature= neg: decrease temp
Q= heat= +: heat flows into system, - : heat flows out of system
W= work= +: work is done by the system (expansion), -: work is done on the system (compression).

You can think of T as temperature, Q as heat, and W as pressure.

The first law of thermodynamics is a statement of conservation of energy: the total energy in the universe can never decrease or increase.

Question 23

Q

3 (Equation) What is the equation for temperature change without phase change?

Answer

A

q=mc∆T

q= heat
m= mass
c= specific heat value
T= change in temperature (generally Kelvin)

Question 24

Q

3 (Equation): What is the equation for an isothermal process, and what is an example?

Answer

A

Q = W because (ΔU = 0)

Isothermal means no temperature change.
ΔU= temperature
Q= heat
W= work (or pressure)

Temperature= heat - pressure

An example would be a boiling pot of water. It stays the same temperature.

Question 25

Q

3 (Equation): What is the equation for an adiabatic process, and what is an example?

Answer

A

Adiabatic= no heat exchange

ΔU = −W because (Q = 0)

Adiabatic= no heat exchange (A (absence diabtic= diablo- no heat)

ΔU= temperature
Q= heat
W= work (or pressure)

Example: Pot without a heat source, just being pressurized.

Question 26

Q

3 (Equation): What is the equation for an isobaric process, and what is an example?

Answer

A

Pressure is held constant.
Multiple forms.

A pot that is open to the air that is being heated.

It should be noted, something could be isobaric and isothermic.

Question 27

Q

3 (Equation): What is the equation for an isochoric process, and what is an example?

Answer

A

Isochoric= same volume, so there is no work

ΔU = Q because  (W = 0)

An example is a pressure cooker with a lid. The volume is going to be the same.

Question 28

Q

3 (Equation) What is the equation for entropy?

Answer

A

ΔS= entropy

Key concept: The universe is a closed, expanding system, so you know that the entropy of the universe is always increasing. The more space that appears with the expansion of the universe, the more space there is for the entire universe’s energy to be distributed and the total entropy of the universe to increase irreversibly.

Question 29

Q

4 (Equation) What is the equation for Density?

Answer

A

ρ=density
m= mass
V= volume

Question 30

Q

4(Equation) Weight of a fluid.

Answer

A

F_g=ρVg

or F_g=gm

Note= the difference in these equations is that in the first one, you don’t know the mass but you know density (taken from the density equation of p=m/v), and in the second one you do know the equation.

F_g= weight
ρ = density
V=volume
g= acceleration due to gravity (9.8 or 10m/s²)

Question 31

Q

4 (Equation) What is the equation for specific gravity?

Answer

A

ρ=density of substance over the specific gravity of water

** The value of SG is going to be unitless. It just tells you if it will float or not. If it is greater than 1, it will sink in water. If it is less than 1, it is less dense and it will float.

Question 32

Q

4 (Equation) What is the equation for pressure?

Answer

A

P=pressure

Units for pressure= pascal (Pa) which equals
1Pa= 1 N/m²=
1atm= 760 torr= 760 mmHg =110,130 Pa

F=force (N)
A= area (m²)

Question 33

Q

4 (Equation) What is the equation for hydrostatic pressure?

Answer

A

P=P_o + ρgz

P=absolute pressure
P_o= incident or ambient pressure (does not always mean ambient pressure, however, in general, 1 atm)
ρ= density of the fluid
g= acceleration due to gravity (9.8 m/s²)
z= depth of the object

Question 34

Q

4 (Equation) What is the equation for gauge pressure?

Answer

A

It’s important to note that because the Incident or ambient pressure generally equals the atmospheric pressure, the equation just results to P_gauge= ρgz

The longer version of this is:
P_gauge=P-P_atm= (P_o +ρgz)-P_atm

P_gauge= pressure of the gage
P= total pressure
P_atm= pressure outside the closed system
P_o= incident or ambient pressure (does not always mean ambient pressure, however, in general, 1 atm)
ρ= density of the fluid NOT object
g= acceleration due to gravity
z= depth of the object

Question 35

Q

4 (Equation) What is application of Pascal’s law to hydraulic machine and mechanical advantage?

Answer

A

P= pressure
F₁=downward force on piston 1
A₁= Surface area of piston 1
F₂= the upward force on piston 2
A₂= the surface area of piston 2

Similar the the equation F=W=P∆V in that P=W/∆V

Question 36

Q

4 (Equation) What is the equation for Buoyance?

Answer

A

F_buoy=ρ_fluid V_{fluid displaced}g= ρ_fluidV_submerged g

F_g,b= m_bg=ρ_bV_bg

F_buey= upwards
ρ_fluid= density of fluid (NOT DENSITY OF OBJECT)
V_{fluid displaced}=fluid displaced
g= force exerted by gravity
ρ_fluid = density of fluid displaced (NOT DENSITY OF OBJECT)
V_submerged =volume of the object submerged

Question 37

Q

4 (Equation) What is the equation to calculate the rate of flow through a pipe or confined space?

Answer

A

Q= flow rate (volume flowing per time)
r= radius of the tube
∆P= the pressure gradient
η= viscosity of the fluid
L=length of the pipe

Key Point: The MCAT really will not test on this equation. However, it does want you to know that the flow will increase if the radius increases (by an exponent of 4). So it’s important to know that a slight change in the radius may have a significant effect on the pressure gradient.

Question 38

Q

4 (Equation) What is Bernoulli’s equation for static pressure and dynamic pressure?

Answer

A

P= absolute pressure of the fluid
ρ= density of the fluid
v= linear speed
g= the acceleration due to gravity
h= the height of the fluid above some datum

Pressure + KE + Potential Energy= Pressure + KE + Potential Energy

Key Point: in the end, Bernoulli’s equation is nothing other than a statement of energy conservation: more energy dedicated toward fluid movement means less energy dedicated toward static fluid pressure. Also, the inverse is true: more static pressure means less movement.

If they are the same height you can ignore the ρgh because they will be the same on both sides

It tells us that when the liquid speeds up, its pressure goes down.

Question 39

Q

4 (Equation) What is the equation that compares area and flow in a tube? i.e. when one tube increases in diameter, what happens to the speed of the flow?

Answer

A

Q=A₁v₁=A₂v₂

A= area (remember, area = πr²
v= speed in m/s

Question 40

Q

5 (Equation) What is the equation for Coulomb’s Law?

I.E. The electrostatic force between two charges.

Answer

A

F_e= the electrostatic force between two charges
k= Coulomb’s constant
q₁ & q₂= the magnitude of the two charges
r= distance between charges.

** it’s important to note that force will change by a magnitude of distance squared when they forces are separated.

Very similar to the equation for gravitational force

Question 41

Q

5 (Equation) What is the equation for the magnitude of an electric field?

Or electric field magnitude

Answer

A

E= the electric field magnitude in newtons per coulomb
F_e= magnitude of the force felt by the test charge q
q= test charge
k= electrostatic constant 8.99×10⁹ (N⋅m²)/C²)
Q=is the source charge magnitude
r= distance between the charges

Key Concept: by dividing coulomb’s law by the magnitude of the test charge, we arrive at two ways of determining the magnitude of the electric field at a point in space around the source charge.

Note: the second equation does not require a test charge.

Question 42

Q

5 (Equation) What is the equation for electric potential energy?

POTENTIAL ENERGY
not
ELECTRIC POTENTIAL

Answer

A

U= electric potential energy

k= electrostatic constant 8.99×10⁹ (N⋅m²)/C^²

Q= the source charge magnitude= electron x (e=1.6x10^-19 C)

q= the test charge magnitude = electron x (e=1.6x10^-19)

r= radius

Question 43

Q

5 (Equation) What is the equation for the electric potential?

Answer

A

V= electric potential measured in volts (V) (1 V = 1 J/C)

U= electric potential energy

q= the test charge magnitude = electron x (e=1.6x10^-19 C)

Q= the source charge magnitude= electron x (e=1.6x10^-19 C)

k= electrostatic constant 8.99×10⁹ (N⋅m²)/C²

²

Question 44

Q

5 (Equation) What are the four equations that you should know for the MCAT based off of coulomb’s law?

Answer

A

From left to right, multiply by R
From top to bottom, divide by q

Question 45

Q

5 (Equation) What is the equation of a magnetic field from a wire (straight wire)?

Answer

A

B= magnetic field
r= distance from the wire
µ ₀= permeability of free space
I= current

Question 46

Q

5 (Equation) What is the equation of a magnetic field for a loop wire?

Answer

A

B= magnetic field
r= distance from the wire
µ₀= permeability of free space
I= current

Note, it is the same equation, just without the pi.

This gives the magnitude of the magnetic field only at the center of the circular loop of current carrying wire with a radius r.

Question 47

Q

5 (Equation) What is the equation for the magnetic force exerted on an object moving by?

Answer

A

F_b=qvBsinӨ

F_b= the magnetic force
q= the charge of the moving object
v= the velocity of the moving charge
B= magnitude of the magnetic field
Ө= the smallest angle between the velocity vector and the magnetic field.

Question 48

Q

5 (Equation) What is the equation for the magnetic force exerted on an object moving by a current-carrying wire?

Answer

A

F_b=ILBsinӨ

F_b= the magnetic force
I= The current
L= length of the wire field
B= magnitude of the magnetic field
Ө= the smallest angle between the velocity vector and the magnetic field.

Question 49

Q

6 (Equation) What is the equation for current?

Answer

A

Q= charge (coulomb)
∆t= time (seconds)
I= current (Ampere= coulomb per second)

Question 50

Q

6 (Equation) What is the equation for determining the resistance of a wire?

like the intrinsic resistance of a physical wire itself

Answer

A

R= resistance (measured in Ohms (Ω).
L= length of the resistor
ρ= resistivity- characterizes the intrinsic resistance to current flow
A= cross sectional area.

Question 51

Q

6 (Equation) What is Ohm’s law and what does it mean?

Or, what is the equation for voltage drop with a given resistance?

Answer

A

V=IR

V= voltage drop
I= current
R= magnitude of resistance

Ohm’s law states that for a given resistance, the magnitude of the current through a resistor is proportional to the voltage drop across the resistor.

Question 52

Q

6 (Equation) What is the equation for power in a resistor?

Answer

A

P= Power
I= current through the resistor
V= voltage drop across the resistor
R= resistance of the resistor.

Real World: Because power equals voltage times current, power companies can manipulate these two values while keeping power constant. One option is to increase current, which results in a decrease in voltage. The other option would be to increase voltage, thus decreasing the current. Power lines are high-voltage lines, which allows them to carry a smaller current—thus decreasing the amount of energy lost from the system.

Question 53

Q

6 (Equation) How do you calculate the amount of resistance with resistors in a series?

Answer

A

R_total= R₁ + R₂ + R₃…

Key concept: When there is only one path for the current to take, the current will be the same at every point in the line, including through every resistor. Once you know the current of the whole circuit, you can use V=IR to solve for the voltage drop across each resistor (assuming that you know the resistance of the resistors).

Question 54

Q

6 (Equation) How do you calculate the amount of resistance with resistors in parallel ?

Question 55

Q

6 (Equation) What is the equation that relates power, current, voltage, and resistance?

Question 56

Q

6 (Equation) What is the equation for capacitance?

Answer

A

C= Capacitance
Q= Charge (+Q on the positive plate and -Q on the negative plate)
V= Voltage

Question 57

Q

6 (Equation) What is the equation for capacitance in a parallel plate capacitor?

Answer

A

C= capacitance
ε= permittivity of free space (8.85 x 10^-12 F/m) (F= farad= 1 C/V NOT faraday’s constant)
A= the area of overlap of the two plates
d= the separation of the two plates.

FYI- the other equation for capicitance is c=Q/V

Capacitance will increase if you increase the area or decrease the distance

Question 58

Q

6 (Equation) What is the equation for the potential energy of the capacitor?

Answer

A

U= potential energy of capacitor
C= capacitance
V= voltage

Question 59

Q

6 (Equation) What is the equation for capacitance due to a dielectric material?

Answer

A

C’=κC

C’ = the new capacitance
κ= dielectric constant
C= original capacitance

Key Concept: It’s important to note that a dielectric material can never decrease the capacitance; thus k can never be less than 1.

Question 60

Q

6 (Equation) What’s the equation for capacitors that are added in parallel?

Question 61

Q

6 (Equation) What’s the equation for capacitors that are added in series?

Question 62

Q

6 (Equation) What’s the equation for capacitors that are added in series?

Question 63

Q

7 (Equation) What is the equation for the speed of sound in a given medium?

Answer

A

b=Bulk modulus (a measure of the medium’s resistance to compression)
ρ= density of the medium
v= speed of sound

Sound and air has like no resistance to compression. That’s why air propagates sound more slowly than solids.

What is the bulk modulus? The relevant elastic property is the bulk modulus, B. This tells us how much a medium’s volume changes when the pressure on it changes.

Question 64

Q

7 (Equation) What is the equation for the doppler effect?

Answer

A

f’=is the perceived frequency (Hz)
f= actual emitted frequency (Hz)
v= speed of sound in a medium (340 m/s)
v_d= the speed of sound of the detector (you listening to the siren)
v_s= speed of the source

Note both the + and – signs. The upper sign (+) should be used when the detector (you) is moving source is moving toward the other object (ambulance). The lower sign should be used when the detector (you) or source is moving away from the other object (ambulance).

Answer 59

A

I= intensity (W/m²)
P= power (Watts)
A= area (m²)

Real world: the power delivered across the surface such as the tympanic membrane is equal to the product of the intensity I and the surface area A, assuming the intensity is uniformly distributed.

Answer 60

A

β= sound level, measured in decibels (dB)
I= intensity of the sound
I_O= threshold of hearing (1x10^-12 W/m²)

Answer 61

A

λ= wavelength
L= length
n= the harmonic, which corresponds to the number of half-wavelengths supported by the string (easy way to remember: number of antinodes)

Answer 62

A

Pitch is a result of the frequency

f= frequency (Hz)
n= harmonic (number of antinodes)
v= speed of the wave (m/s)
L= length (m)

Answer 63

A

λ= wavelength of standing wave in closed pipe
L= length
n= the harmonic, which corresponds to the number of half-wavelengths supported by the string. This can only be odd integers (n= 1,3,5 and so on)

Answer 64

A

f= frequency
v= speed of the wave
L= length
n= the harmonic, which corresponds to the number of half-wavelengths supported by the string. This can only be odd integers (n= 1,3,5 and so on)

Answer 65

A

m= magnification (unitless)
i= distance between image and the mirror
o= distance between the object and the mirror

note the negative sign

When the image is less than than the object distance, the object is minimized. When the image distance is greater than the object distance, the object is magnified.

magnification
| m |>1 indicates magnification

magnification
| m |<1 indicates minimization

m |> 1 indicates

Answer 66

A

n= dimensionless quality called the index of refraction of the medium
c= speed of light in a vacuum
v= speed of light in a medium
FYI: to give context, the index of refraction of air is 1