Source: Revised GRE PDF 1st Ed. Section 4: Verbal; #21 (p. 67)

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Which of the following statements is supported

Which of the following statements is supported by the passage? A tall tree can transport a hundred gallons of water a day from its roots deep underground to the treetop. Is this movement propelled by pulling the water from above or pushing it from below? The pull mechanism has long been favored by most scientists. First proposed in the late 1800s, the theory relies on a property of water not commonly associated with fluids:its tensile strength. Instead of making a clean break, water evaporating from treetops tugs on the remaining water molecules, with that tug extending from molecule to molecule all the way down to the roots. The tree itself does not actually push or pull; all the energy for lifting water comes from the sun’s evaporative power. Blank: The pull theory is not universally accepted by scientists., The pull theory depends on one of water’s physical properties., The pull theory originated earlier than did the push theory.

2 Explanations

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Kartik Dadwal

but where does it say tensile strength is a physical property? How can we assume it? please help us solve this problem! We always have to make sure answer is completely correct/acceptable but using word 'physical' makes it dubitable.

Thanks!

Jul 4, 2013 • Comment

Sam Kinsman, Magoosh Tutor

Hi Kartik,

That's a good question! Let me explain.

The word "property" refers to a trait or characteristic. For example, one of the properties of copper is that it conducts electricity. One of the properties of water is that it boils at 100 Celsius.

The word "physical" is an adjective - it describes things that have to do with matter that we can touch.

Thus, "physical property" refers to a characteristic that is related to actual matter that can be touched.

The passage tells us that "water evaporating from treetops tugs on the remaining water molecules, with that tug extending from molecule to molecule all the way down to the roots." So the water molecules are physically touching each other, and they pull on each other.

This is a characteristic of water, and it has to do with physical matter. Therefore, we can conclude that tensile strength is a physical property of water.

Aug 30, 2018 • Reply

2

Gravatar Chris Lele, Magoosh Tutor

Sep 26, 2012 • Comment

Kanav Batra

The passage doesn't explicitly state that the tensile strength is a physical property, is this something we have to deduce from common knowledge?

Aug 29, 2018 • Reply

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