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PS and BS questions (how appropriate)

Discussion in 'MCAT Discussions' started by athena21, Aug 12, 2002.

  1. athena21

    athena21 Senior Member

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    Hey guys,
    I'm having trouble figuring these out from AAMC V. Please help!

    130) From ground level, a person at Point A throws a snowball horizontally to the right at 25 m/s. Where does the snowball land? (Point A is actually on top of a hill 20m above ground, point B is horizontally 50m away on level ground.) Answer is B, don't know how!
    A) 10 m to the left of Point B
    B) At point B
    C) 12.5 m to the right of Point B
    D) 50 m to the right of point B

    179) If an artery that supplies blood to a lung lobe was blocked but ventilation to the lobe was unaffected, how would alveolar gas partial pressures change? (Answer C why?)
    A) Both P(O2) and P(CO2) would increase
    B) Both P(O2) and P(CO2) would decrease
    C) P(O2) would increase and P(CO2) would decrease
    D) opposite of C

    Which is more soluble in water? THF or Toluene? The answer is THF because its hydrogen bonds are stronger with water than tolene's, but i thought ethers (THF) don't hydrogen bond!

    Is urine hypertonic or hypotonic to the blood?

    To correct nearsightedness, you use a divergent lens as the image focuses in front of the retina. Does that mean you use a convergent lens to correct farsightedness when the image forms behind the retina?

    Any help would be much appreciated.

    Thanks! We're almost done so hang in there!
     
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  3. rCubed

    rCubed taiko master

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    for 130)

    this is an example of projectile motion, so u have to take the X and Y components differently.

    First of all, u know that along the Y axis,

    the initial velocity is 0
    the height is 20 m
    acceleration is g

    so, using the equation Y=V(i)t + 1/2 g t^2
    20= 1/2 g t^2

    --> t= 2 sec

    then we can use the time and stick it into equations along the X axis:
    where initial velocity is 25 m/s
    and there is no acceleration

    X= V(i)t + 1/2 g t^2

    = 25 * 2
    = 50 m
    which is point B
     
  4. limit

    limit Molesting my inner-child

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    #130)
    x = vt
    We know the velocity (25) and we want to find out x (distance), so all we need is t (the time the ball spends in the air).

    For t, we use the formula h = (1/2) a t^2 -- to find out the time it takes for the ball to hit the ground, which will in essence tell us the time it spends in flight. Solving for t, t = 2 seconds. Going back to our original formula, x = vt = (25)(2) = 50, which is right on the money.

    #179)
    Pay attention to what this question is telling and asking: ventilation to the lobe is unaffected, but blood flow is blocked. Blood is what brings carbon dioxide in exchange for oxygen to bring back to the heart and consequently the tissues. Without this exchange, the gas partial pressures will resemble the atmospheric pressure (with which they are having the ventilation). As you know, atmosphere is more O2 than CO2.

    Next one (you didn't provide number), you are correct THF can H-bond, and Toluene can NOT. THF can h-bond because it has an electronegative atom, O. Toluene is just an aromatic. The correct answer should thus be that THF can h-bond, and toluene can't. If that is not the correct answer choice, then its an error. The "strength" of h-bonds here is not an issue.

    Urine is hypertonic (good way to think about this is -- its "salty" or whatever -- not like I've tasted it :laugh: ) to the blood... For this we have to thank the loop of Henle and the collecting duct for absorbing water along the nephron.

    "To correct nearsightedness, you use a divergent lens as the image focuses in front of the retina. Does that mean you use a convergent lens to correct farsightedness when the image forms behind the retina?"
    Yes, that's correct.

    Limit
     
  5. athena21

    athena21 Senior Member

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    thanks so much! you guys are awesome!
     

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