Question 36

[sharra.26428]

Ok I understand this question and the answer does make sense. With that said I am just wondering if this is the kind of detail we should be expecting from the MCAT in terms of solving numerical problems. I am doing kaplan and aamc tests along with yours and i am not sure if it is just me but these kind of detailed calculations i only encounter in your tests. A helpful explanation would be appreciated.
thanks

[admin]

Actually, these practice MCAT CBTs are modeled after the more challenging real past MCAT CBTs. Even in your practice AAMC MCATs, you will find that at least every second test will have 1-2 questions with more detailed calculations.

It's not to say that you must spend the time or energy during an exam to get a question with a long calculation right. After all, one question will not significantly affect your score. It is possible to get a 13 or 14 on any science subtest while ignoring (guessing) on the questions that occupy too much time.

[?!]

I understand the calculations for this problem, but I'm having a problem with figuring out why the reflection of 90% of solar radiation was not included in the calculation.

The question only mentions solar radiation being incident on the telescope, hence, only 10% of the radiation would result in heat. But the answer used the whole 120Wm-2 and not 10% of that...

Could someone please help me?

[admin]

I understand your dilemma, but the question is specifically asking about the “circulating system of coolant” method of regulating temperature. The question stem describes the “channel covering the entire exposed surface” which implies exposure to the sun (i.e. the incident ray which would be taken at 100%).

Now let us use the context of the passage which begins with “Keeping warm in cold climates and cool in tropical climates”; then the second paragraph talks about a reflective surface (presumably to help heating) and then the 3rd paragraph and question stem describes a coolant system (to take heat away from the satellite by heating up the water and circulating). To connect the two systems together (reflection and coolant) would be counterproductive (like in homeostasis, you would want the systems to turn on/off according to need to keep the system in a dynamic equilibrium).