Physics

Question 1

Eq for Gibbs free energy

Answer 1

Question 2

Gibbs Free Energy eq. as it relates to equilibrium of a rx

Answer 2

Question 3

How would you find the delta G formation of a product in a reaction?

Answer 3

Use the equation:

delta G (of rx) = free energy formation of products - free energy of reactants

Put in known values and solve

Question 4

How do you change the speed of a sound?

Answer 4

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

Question 5

How does ultrasound medical equipment work?

Answer 5

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

Question 6

How do you write two thousandths? How about three thousandths?

Answer 6

0. 002
1. 003

Question 7

What type of wave is a sound wave?

Answer 7

Longitudinal NOT transverse

Question 8

What equations/concepts should you think about when presented with a question about intensity of sound and converting to decibels?

Answer 8

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)

Question 9

What is the difference between in phase and out of phase waves?

Answer 9

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.

Question 10

What are the SI units for:

Voltage

Current

Resistance

Power

Frequency

Wavelength

Answer 10

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

Question 11

Myopia

Answer 11

Nearsidedness

Need concex lenses, focal point too close (in front )

Question 12

Hyperopia

Answer 12

(farsighted)

Need converging lenses, focal point is too far (behind eye)

Question 13

What is the equation for hydrostatic pressure?

Answer 13

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

Question 14

You are given an IR spec with some valleys. What should you be looking for/at?

Answer 14

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

Question 15

You are reading a passage about NMR spectroscopy, what are some ideas you should be thinking about?

Answer 15

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

Question 16

Equation for BP or change in pressure (from one part of the blood system to the other)

Answer 16

bp=cardiac output (CO) * total peripheral resistance

delta P= QxR
Q=Blood flow
R=Resistance

*Relates to V=IR for current

Question 17

Define paramagnetic

Answer 17

very weakly attracted by the poles of a magnet, but not retaining any permanent magnetism

ex. Oxygen (has two unpaired electrons)

Question 18

What are the SI units for a Tesla?

Answer 18

Magnetic field is measured in Teslas

SI= (N*s)/(C*m)

Newtons are units of force

SI= (kg*m)/s²

Question 19

How does an MRI produce images?

Answer 19

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.

Question 20

You are given a question about energy of a photon. What are some equations/relationships you should think about?

Answer 20

Question 21

When approached with linear motion problems, what are some equations/concepts to keep in mind?

Answer 21

acceleration and velocity are along the same line of motion

VAT: V_f=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 V_f)

if a=constant, you can use x=vt (where v is average velocity)

Question 22

What is the difference between alpha, beta and gamma decay?

Answer 22

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

Question 23

What is the thin lense equation? When a question asks about optics, what should you be thinking about?

Answer 23

1/f=1/o+1/i

f=focal point

o=object distance

i=image distance

IR=inverted and real

UV=upright and virtual

Question 24

What is the photoelectric effect and what two equations should you know?

Answer 24

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

Question 25

What are newtons three laws?

Answer 25

1. object moving/at rest will remain moving/at rest unless acted upon by external force
2. F=ma
3. equal and opposite

Question 26

how do isotopes differ?

Answer 26

isotopes have the same number of protons, atomic number, but different number of neutrons

Question 27

how do you calculate conductivity?

Answer 27

1/R

conductivity=ability to conduct current