Physics Flashcards
Eq for Gibbs free energy
Gibbs Free Energy eq. as it relates to equilibrium of a rx
How would you find the delta G formation of a product in a reaction?
Use the equation:
delta G (of rx) = free energy formation of products - free energy of reactants
Put in known values and solve
How do you change the speed of a sound?
The only way to change the speed of a sound is to change the environment in which the sound is moving.
Ex. humidity, temperature, phase
Sound travels fastest in solids, then liquids then gasses
Warmer temp=faster speed
How does ultrasound medical equipment work?
A transducer is placed on, for example, the belly of a pregnant woman and converts electric energy into sound waves (with higher frequency than what the human ear can hear). Ideal=high frequency and low wavelength. This makes it so we have less diffraction, which is good! Too much and we get blurry pictures
How do you write two thousandths? How about three thousandths?
- 002
- 003
What type of wave is a sound wave?
Longitudinal NOT transverse
What equations/concepts should you think about when presented with a question about intensity of sound and converting to decibels?
Intensity (I) = Power/Area, so the further away someome is from a noise, the intensity decreases by a factor of (distance)2
dB=10xlong10(I/I0) where I0 is the human threshold of hearing (10-12)
What is the difference between in phase and out of phase waves?
In phase: if two in phase waves arrive at the same place at the same time, the effect doubles (if we want to destroy a kidney stone we would want in phase waves)
Out of phase: If two out of phase waves arrive at the same time, they will likely cancel each other out.
What are the SI units for:
Voltage
Current
Resistance
Power
Frequency
Wavelength
volts= J/C
Amps= C/s
Ohms= (J*s)/C2
Watts= J/s (kg*m2*s-3)
Note about SI units
Joules: (kg*m2*s-2) = N*m
Newton: kg*(m/s2)
Frequency: Hrtz=1/s
Wavelength: meters= m
Myopia
Nearsidedness
Need concex lenses, focal point too close (in front )
Hyperopia
(farsighted)
Need converging lenses, focal point is too far (behind eye)
What is the equation for hydrostatic pressure?
hydrostatic pressure=P= P+ pgz (where z is depth). so pressure is directly proportional to depth, or inversely proportional to height. So when someone faints, it is their body decreasing the height and therefore increasing the bp in the brain. Evolutionarily this makes sense-if bp drops in brain, fainting puts your brain at the same height relative to the rest of your body and prevents bp dropping more
You are given an IR spec with some valleys. What should you be looking for/at?
IR=infa red light being shot at an object (molecule) can tells us what functional groups are present
N-H (3200-3600) sharp
O-H (3200-3600) wide/broad
C=O 1700 sharp
*just because you have an O-H and C=O does not mean you have a carboxylic acid. You probably do, but not necessarily
You are reading a passage about NMR spectroscopy, what are some ideas you should be thinking about?
NMR Spec: Deals with magnetic shift in nuclei (protons vibrating) when a magnetic field is applied. It measures peaks, excited nuclei.
High electron density=shielding=upfield=further right
less change from magnetic field applied (smaller number)
Low electron density=little protection=big changes.
deshielding=downfield=further left (bigger number)
Most deshielded:
COOH 10-13ppm
CHO 9-10 ppm
aromatic 6-8 ppm
Equation for BP or change in pressure (from one part of the blood system to the other)
bp=cardiac output (CO) * total peripheral resistance
delta P= QxR
Q=Blood flow
R=Resistance
*Relates to V=IR for current
Define paramagnetic
very weakly attracted by the poles of a magnet, but not retaining any permanent magnetism
ex. Oxygen (has two unpaired electrons)
What are the SI units for a Tesla?
Magnetic field is measured in Teslas
SI= (N*s)/(C*m)
Newtons are units of force
SI= (kg*m)/s2
How does an MRI produce images?
NIH: MRIs employ powerful magnets which produce a strong magnetic field that forces protons in the body to align with that field (magnetic moment). When a radiofrequency current is then pulsed through the patient, the protons are stimulated, and spin out of equilibrium, straining against the pull of the magnetic field. When the radiofrequency field is turned off, the MRI sensors are able to detect the energy released as the protons realign with the magnetic field. The time it takes for the protons to realign with the magnetic field, as well as the amount of energy released, changes depending on the environment and the chemical nature of the molecules. Physicians are able to tell the difference between various types of tissues based on these magnetic properties.
In order to have a magnetic moment, nuclei must have an odd number of odd number of protons or an odd number of neutrons or both have an overall spin.
Nuclei with an identical number of protons and neutrons cancel out their overall spins.
You are given a question about energy of a photon. What are some equations/relationships you should think about?
When approached with linear motion problems, what are some equations/concepts to keep in mind?
acceleration and velocity are along the same line of motion
VAT: Vf=V0+at (use when you dont need x)
VAX: V2=V02+2ax (use when you dont need t)
VTAT: x=V0t+((at2)/2), (use when you dont need Vf)
if a=constant, you can use x=vt (where v is average velocity)
What is the difference between alpha, beta and gamma decay?
alpha: alpha particles have 2 protons and 2 neutrons (similar to Helium), positively charged
beta: beta particles are high speed electrons or positron, positive or negative charge. In beta minus B- a neutron turns to proton (ie was more negative), whereas in beta plus B+ a protons turns into a neutron (was more positive)
gamma: gamma particles are photons that carry energy in the form of electromagnetic waves, nor charged particles
What is the thin lense equation? When a question asks about optics, what should you be thinking about?
1/f=1/o+1/i
f=focal point
o=object distance
i=image distance
IR=inverted and real
UV=upright and virtual
What is the photoelectric effect and what two equations should you know?
The photoelectric effect is the emission of electrons or other free carriers when electromagnetic radiation, like light, hits a material.
Energy=hf=hc/lamda
Kinetic energy=hf-W
h=constant
W=work
What are newtons three laws?
- object moving/at rest will remain moving/at rest unless acted upon by external force
- F=ma
- equal and opposite
how do isotopes differ?
isotopes have the same number of protons, atomic number, but different number of neutrons
how do you calculate conductivity?
1/R
conductivity=ability to conduct current
