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- May 24, 2014
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I'm applying to be a Kaplan tutor, and was given some questions to be able to explain to the instructor. I feel pretty confident about my answers, but I really don't want to mess up so I'd appreciate if someone could read over my answers and reasonings and see if they agree.
1) Three identical charges of magnitude q are equidistant from a point A. What is the electric potential?
my answer: 3kq/r
my reasoning: The equation that gives the electric potential at a certain point is kq/r. Electric potential is a scalar quantity, meaning that the direction of the charges around the point doesn't matter, the only thing that matters is that they are all equidistant (same r). For this reason, you can simply add up the electric potentials, so kq/r +kq/r+ kq/r= 3kq/r
2) Helium gas behaves more ideally than CO2 gas. Which explains why this is so?
I. CO2 exerts a greater pressure because its molecules have lesser volume.
II. The intermolecular forces between CO2 molecules are stronger than those in He.
III. Helium molecules have greater kinetic energy, and therefore behave more ideally.
my answer: II only
my explanation: Although having a greater pressure would make a gas behave nonideally, I isn't true because co2 molecules have a greater volume than He molecules. II is true because co2 is capable of experiencing instantaneous dipole moments which could cause intermolecular attraction/ repulsion, while He molecules can't experience this because they are lone atoms. Intermolecular forces are not accounted for in the ideal gas law, so co2's van der waal's forces cause non-ideal behavior. III is not true because co2 is heavier than He, and KE=1/2mv^2, so He molecules would have less KE (assuming equal v)
This next one is the one I'm least sure about.
Normally, dexamethasone (a synthetic glucocorticoid) inhibits ACTH secretion and, consequently, cortisol secretion. A patient with low ACTH and elevated cortisol levels after dexamethasone administration most likely has:
A. An adrenal cortical tumor.
B. A hypothalamic tumor.
C. An anterior pituitary tumor.
D. No pathology in endogenous cortisol production.
my answer: A
my explanation: Since ACTH stimulates cortisol secretion, it would be expected that a decrease in ACTH would cause a decrease in cortisol levels. Since this didn't happen, it is likely that the problem is "after" the pituitary in the hormone pathway. Because of this, I would expect the patient to suffer from an adrenal cortical tumor that is causing an increased release of cortisol.
Thanks so much and let me know if you agree/disagree!
1) Three identical charges of magnitude q are equidistant from a point A. What is the electric potential?
my answer: 3kq/r
my reasoning: The equation that gives the electric potential at a certain point is kq/r. Electric potential is a scalar quantity, meaning that the direction of the charges around the point doesn't matter, the only thing that matters is that they are all equidistant (same r). For this reason, you can simply add up the electric potentials, so kq/r +kq/r+ kq/r= 3kq/r
2) Helium gas behaves more ideally than CO2 gas. Which explains why this is so?
I. CO2 exerts a greater pressure because its molecules have lesser volume.
II. The intermolecular forces between CO2 molecules are stronger than those in He.
III. Helium molecules have greater kinetic energy, and therefore behave more ideally.
my answer: II only
my explanation: Although having a greater pressure would make a gas behave nonideally, I isn't true because co2 molecules have a greater volume than He molecules. II is true because co2 is capable of experiencing instantaneous dipole moments which could cause intermolecular attraction/ repulsion, while He molecules can't experience this because they are lone atoms. Intermolecular forces are not accounted for in the ideal gas law, so co2's van der waal's forces cause non-ideal behavior. III is not true because co2 is heavier than He, and KE=1/2mv^2, so He molecules would have less KE (assuming equal v)
This next one is the one I'm least sure about.
Normally, dexamethasone (a synthetic glucocorticoid) inhibits ACTH secretion and, consequently, cortisol secretion. A patient with low ACTH and elevated cortisol levels after dexamethasone administration most likely has:
A. An adrenal cortical tumor.
B. A hypothalamic tumor.
C. An anterior pituitary tumor.
D. No pathology in endogenous cortisol production.
my answer: A
my explanation: Since ACTH stimulates cortisol secretion, it would be expected that a decrease in ACTH would cause a decrease in cortisol levels. Since this didn't happen, it is likely that the problem is "after" the pituitary in the hormone pathway. Because of this, I would expect the patient to suffer from an adrenal cortical tumor that is causing an increased release of cortisol.
Thanks so much and let me know if you agree/disagree!
