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Re: MCAT practice questions

Posted: Fri Jul 31, 2015 9:38 am
by goldstandard_mcat
A block of wood is held half immersed in the water. When released, it submerged to a greater degree but remained afloat. When the block was initially released, which of the following must have been true?

1) Weight of fluid displaced > weight of block
2) Density of fluid < density of block
3) Initial buoyant force < maximum buoyant force
4) Maximum buoyant force = half the weight of the block

Correct Answer: 3

Tricky! You must recognize that the half immersed block would submerge as long as its density is greater than ½ the density of water or a specific gravity of 0.5. Thus this block may: (i) have a specific gravity between 0.5 and 1.0 (which means the block's density would be less than that of water); or (ii) it could have a density equal to that of water; but (iii) it could NOT have a density greater than that of water (this would make it sink to the bottom but the question says that it remains afloat so (iii) is not possible): nonetheless, it would submerge from a position of being held half immersed [thus answer choice B. is not the best answer because of the preceding points (i) and (ii)]. When the block sinks, it will certainly displace more water than it did initially; therefore, the buoyant force increases to its maximum.{cf. Archimedes Principle}

Re: MCAT practice questions

Posted: Wed Aug 12, 2015 6:45 am
by goldstandard_mcat
How would Jenny, a salesperson at an organic pre-made meals company, use the door-in-the-face technique to persuade people who do not want to subscribe to purchase the meals?

A. Ask individuals if they want to subscribe to the meals for two years, and then later scale it down to a month.
B. Ask individuals if they want to subscribe to the meals, and if they are interested, say that they should do so immediately because the 15% discount will end within two days.
C. Ask individuals if they want to subscribe to the meals using a trial basis of one week. Once they agree, she would then ask if they want a six-month subscription.
D. Ask individuals if they want to subscribe to the meals and then hand out a flyer of endorsements given by famous chefs.
Correct Answer: A
Foundational Concept: 7
Biological, psychological, and sociocultural factors influence behavior and behavior change

Content Category: 7B
Social processes that influence human behavior

Scientific Reasoning and Inquiry Skill: 1
Knowledge of Scientific Concepts and Principles

A is correct. With the door-in-the-face technique, the requester starts with a very large appeal and more often than not will be denied (the door will be slammed in his/her face). The requester then makes a concession and offers a second request, upon which the person being asked will feel that he/she should also make a concession and will more likely accept the offer.

B. This is incorrect. This scenario describes a persuasive technique that relies on using a deadline such as a sale that will end in two days. This produces feelings of anxiety that the same deal will not be offered in the future.
C. This is incorrect. This scenario illustrates the foot-in-the-door technique, which involves asking for a smaller request. Once the requester has the individual’s attention and the requester thus has his/her foot in the door, the requester makes a larger request.
D. This is incorrect. This scenario relies on using testimonials that demonstrate the legitimacy and credibility of the product.

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Re: MCAT practice questions

Posted: Sun Sep 06, 2015 5:11 pm
by goldstandard_mcat
What is the name and frequency of the majority of the electromagnetic waves produced during non–rapid eye movement (NREM) sleep stage 4 (name, frequency, respectively)?

A. Delta, <4 Hz B. Theta, 4–7 Hz C. Alpha, 8–12 Hz D. Beta, 13–24 Hz

Check out the answer and explanation here

Re: MCAT practice questions

Posted: Mon Jul 18, 2016 6:16 am
by goldstandard_mcat
Hi! Here's another free MCAT sample question.

If the sum of all the forces acting on a moving object is zero, the object will:
A. decelerate and stop.
B. accelerate uniformly.
C. change the direction of its motion.
D. continue moving with constant velocity.

Answer: D
Explanation: For something to change direction or accelerate there must be a net force acting on it (Newton’s 2nd Law).
Also, Newton’s 1st Law states that an object in motion will stay in motion at constant velocity (a form of inertia) unless acted upon by a net (an unbalanced) force.

For more MCAT questions, register for a free MCAT practice test here ... ctice-Test

Re: MCAT practice questions

Posted: Tue Sep 13, 2016 11:28 pm
by dhivyaa4n
An aldehyde reacts with a newly-discovered amine to form an imine molecule. Which of the following reaction types took place in this reaction?

A proton transfer
B nucleophilic addition
C acid base reaction
D elimination reaction

Why? Imines are molecules with a carbon nitrogen double bond (similar to a carbonyl, except nitrogen instead of oxygen). In the formation of an imine, the lone pair of electrons on the nitrogen on the amine attack the aldehyde carbon to form a new amine molecule, which after dehydration reaction becomes an imine. Thus (B) is the correct answer.