Heat Flow question (and others)

[DeathandTaxes]

From the diagnostic physics exam on WikiPremed,

True or False:

With the temperature inside kept at 70 degrees Fahrenheit, the heat gain by conduction through the walls of a home will be approximately twice as great if the outside temperature is 90 degrees Fahrenheit compared to an outside temperature of 80 degrees Fahrenheit.

The answer is true because "Rate of heat flow by conduction is proportional to the temperature difference.", but since if the degree is only a 10 degree difference, why would that be considered doubling? The ratio (in Kelvins) would be (353 / 343) vs (363/343), neither of which is twice as great.

Second question:

In the ear, the tympanic membrane has
an area greater than the oval window. A result of
this design is that the total:
'
A. force acting on the oval window is increased.
B. force/unit area acting on the oval window is
decreased.
C. force acting on the oval window is decreased.
D. force/unit area acting on the oval window is
increased

I don't understand how the typhanic membrane even relates to the oval window. I assumed that if area is greater, and force is constant, then pressure in the ear goes down. This would suggest C, but the answer is D. Why is that?

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[NextStepTutor_1]

So, the answer to your question lies in the quote you have. You said that the rate of heat flow is proportional to the temperature difference. And so, the temperature difference between 70 & 80 is 10 , whereas the difference between 70 & 90 is 20. Thus, the rate of heat flow is twice as much for the 70 and 90 case.

 

[DeathandTaxes]

Thanks!

Also updated with another question.

 

[Czarcasm]

Thanks!

Also updated with another question.

Interesting point. I had the same thought process as you at first, but if you realize that pressure is constant (assuming we're at atmospheric pressure or any constant pressure), than increasing area must result in a proportional increase in force to maintain that constant relationship. I suppose it might help if you think of this as one of those hydraulics scenarios where: F1/A1 = F2/A2 (pressure of liquid in container is constant). It would be different if pressure were subject to changing (for example, gas acting on a container that is decreased in volume). In this case, they key thing you need to ask yourself is, what is constant (force or pressure)? Here it would be net pressure acting on the tympanic membrane.

I'm drawing upon old Physics knowledge from 2 years ago, so don't take my word for it.