Physics Equations Combined Flashcards

Question

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

Answer 1

**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.

Answer 2

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.

Answer 3

**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.

Answer 4

**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.

Answer 5

**ρ**=density **m**= mass **V**= volume

Answer 6

**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)

Answer 7

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.

Answer 8

**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)

Answer 9

**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

Answer 10

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

Answer 11

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

Answer 12

**F**_buoy=**ρ**_fluid **V**_{fluid displaced}**g**= **ρ**_fluid**V**_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

Answer 13

* 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.

Answer 14

* **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.

Answer 15

Q=A₁v₁=A₂v₂ A= area (remember, area = πr² v= speed in m/s

Answer 16

**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*

Answer 17

**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.

Answer 18

**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

Answer 19

**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

Answer 20

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

Answer 21

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

Answer 22

**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.

Answer 23

**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.

Answer 24

**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.

Answer 25

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

Answer 26

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

Answer 27

**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.

Answer 28

**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.

Answer 29

**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).

Answer 30

**C = (εA)/d** C= capacitance ε=permittivity A= parallel plate area d= distance between two plates _____________________________________________________________ **C**= Capacitance **Q**= Charge (+Q on the positive plate and -Q on the negative plate) **V**= Voltage

Answer 31

**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*

Answer 32

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

Answer 33

**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.

Answer 34

**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.

Answer 35

**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 36

**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 37

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

Answer 38

**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 39

*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 40

**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 41

**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 42

**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 43

**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

Answer 44

**n1 sinӨ1**= medium from which the light is coming **n2 sinӨ2**=Medium into which the light is entering **n** = you get this value from equation of speed in a medium ( **n=c/v** ) You measure the angles in relation to the ‘critical angle’ down the middle

Answer 45

It's the same for mirrors. **o**= distance between the object and the mirror **i**= distance between the image and the mirror **r**= radius of the curvature **f**= focal point **m**= magnification (unitless) **i**= distance between image and the mirror **o**= distance between the object and the mirror

Answer 46

**P**=power of lens **f**= focal length

Answer 47

**ω=2πf** **ω**= angular frequency (radians) **f**= linear frequency (Hz)

Answer 48

**v= fλ** **v**= Velocity of the wave (m/s) **f**= linear frequency (Hz) **λ**= wavelength (m)

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Physics Equations Combined Flashcards

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