While researching a topic, a student has taken the following notes:Generally, an object will heat up when twisted.The twisting of...
GMAT Expression of Ideas : (Expression) Questions
While researching a topic, a student has taken the following notes:
- Generally, an object will heat up when twisted.
- The twisting of an object is known as torsion.
- A 2019 study led by Zunfeng Liu and Ray Baughman tested the torsional heating of various fibers.
- When a \(\mathrm{3}\)-millimeter-thick sample of thermoplastic polyurethane (TPU) fiber was twisted, its average surface temperature increased by \(\mathrm{6°C}\).
- When a \(\mathrm{4}\)-millimeter-thick sample of styrene-ethylene-butylene-styrene (SEBS) rubber fiber was twisted, its average surface temperature increased by \(\mathrm{3.5°C}\).
The student wants to contrast the two samples. Which choice most effectively uses relevant information from the notes to accomplish this goal?
When the fibers were twisted as part of the 2019 study, the surface temperature of both samples increased.
In 2019, researchers studied the effect of torsional heating on various fibers, including samples of SEBS rubber and TPU.
Twisting an object will generally cause its temperature to increase, a process known as torsional heating.
The SEBS rubber sample used in the 2019 study was thicker than the TPU sample.
Step 1: Decode and Map the Passage
Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'Generally, an object will heat up when twisted.' |
|
| 'The twisting of an object is known as torsion.' |
|
| 'A 2019 study led by Zunfeng Liu and Ray Baughman tested the torsional heating of various fibers.' |
|
| 'When a 3-millimeter-thick sample of thermoplastic polyurethane (TPU) fiber was twisted, its average surface temperature increased by 6°C.' |
|
| 'When a 4-millimeter-thick sample of styrene-ethylene-butylene-styrene (SEBS) rubber fiber was twisted, its average surface temperature increased by 3.5°C.' |
|
Provide Passage Architecture & Core Elements
Main Point: A 2019 study measured how much different fiber samples heat up when twisted, finding specific temperature increases for TPU and SEBS rubber samples.
Step 2: Interpret the Question Precisely
What's being asked? Which choice most effectively contrasts the two fiber samples
What type of answer do we need? A statement that highlights differences between the TPU and SEBS samples
Any limiting keywords? 'contrast' (show differences), 'most effectively' (best option)
Step 3: Prethink the Answer
- Looking at our analysis, the two samples differ in several ways:
- Material type: TPU vs SEBS rubber
- Thickness: 3mm vs 4mm
- Temperature increase: 6°C vs 3.5°C
- The right answer should highlight one of these key differences directly. It should point out a specific way the samples are different from each other, not what they have in common or general background information.
When the fibers were twisted as part of the 2019 study, the surface temperature of both samples increased.
✗ Incorrect
- This states that both samples' temperatures increased, which shows similarity, not contrast
- The question specifically asks to contrast (show differences), but this choice emphasizes what both samples have in common
In 2019, researchers studied the effect of torsional heating on various fibers, including samples of SEBS rubber and TPU.
✗ Incorrect
- This simply mentions that both samples were studied but provides no specific differences
- It fails to show how the samples differ from each other
Twisting an object will generally cause its temperature to increase, a process known as torsional heating.
✗ Incorrect
- This gives general background about torsional heating but doesn't mention the specific samples at all
- Contains no information about either the TPU or SEBS samples to contrast
The SEBS rubber sample used in the 2019 study was thicker than the TPU sample.
✓ Correct
- Directly states that the SEBS rubber sample was thicker than the TPU sample
- This creates a clear contrast by highlighting one specific difference: thickness (4mm vs 3mm)