Self-study
When an ordinary piece of steel is put under pressure, the steel compresses; that is, its volume slightly decreases. ██████ ████████ ██ █ ██████ ██ ██████ ████ ████████████ ██ █████ ████ ███ █████ █████████ ███ ██████ ███████ ██████████ ███ ███████ ██ █ █████ ██ █████ ████ ██ █████ █████████ ████████ ████ ████ ██████ ████ ██ █████ █████ ████ █████████ ██████████ ██ █ ███████ █████████ █████ ██████ ██ ██████ ██ ███ ██████ ██ █ ██████████ █████ ██ █████ ██ ███████ █████████ ███ ██ ███ █████ ██ ████ ██ ███████ ███ ██████ ███████ █████████ ████ ███ █████ ██ █████ ████ ██████████ ████████
Summary
Today, we’re learning about glass. Glass is a fluid, so when it’s put under pressure, its volume stays the same but it flows slowly to an area of lesser pressure. The stimulus proposes an example where an extremely heavy object is placed on the middle of a sheet of glass. So what happens?
Strongly Supported Conclusions
Based on the scenario given, we can see that a heavy object would put pressure on the middle of the sheet of glass. Because glass flows away from pressure without changing in volume, we can infer that over time the sheet of glass would shift away from the pressure, becoming thinner in the middle where the object is, and thicker around the edges.
19.
Which one of the following ████ █████████ █████████ ███ █████████
a
become larger in ████ ███ █████ ██ ██ ███████ █████████
This is anti-supported. Because fluid flows away from areas of higher pressure, the glass would thin out in the part under the heavy object and become thicker in the non-pressured areas. Thus, it would not remain uniformly thick.
b
flow toward the █████ ██ █████ ███ ████████ ██ ███ ██████ ██ ████████
This is anti-supported. The stimulus directly states that fluids flow away from areas of higher pressure. Since glass is a fluid, it would therefore flow away from the point of greatest pressure, not towards.
c
compress, although not ██ ████ ██ █ █████ ██ █████ █████
This is anti-supported. The stimulus explains that glass, as a fluid, does not compress; instead, it flows. Because fluids do not compress, glass would not compress under pressure.
d
divide into exactly ███ ██████ ████ ███ █████ ██ ███████ ████ ███ █████ ██ ███ ████████ █████ ██ █████
This is not supported. The stimulus specifically sets out the condition that the glass would not crack, so it could only divide into two pieces if the glass flowed fully out from underneath the object. And we just don’t have a good sense of whether or not that would happen.
e
be thinner in ███ ███████ ██ ███ █████ ████ ██ █████ ███ ████████ ██ ███ ██████ ████ ██ █████ ████████ ██ ███ █████ ████ ███ ███ █████ ████ ████████
This is strongly supported. We know that glass flows away from pressure. This means it would slowly move away from the pressure created by the object and towards non-pressured areas, causing the sheet to be thinner where there’s pressure and thicker where there isn’t.