When asteroids collide, some collisions cause an asteroid to spin faster; others slow it down. If asteroids are all monoliths—single...
GMAT Reading Comprehension : (RC) Questions
Source: Official Guide
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When asteroids collide, some collisions cause an asteroid to spin faster; others slow it down. If asteroids are all monoliths—single rocks—undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with statistical "tails" of very fast and very slow rotators. If asteroids are rubble piles, however, the tail representing the very fast rotators would be missing, because any loose aggregate spinning faster than once every few hours (depending on the asteroid's bulk density) would fly apart. Researchers have discovered that all but five observed asteroids obey a strict limit on rate of rotation. The exceptions are all smaller than 200 meters in diameter, with an abrupt cutoff for asteroids larger than that.
The evident conclusion—that asteroids larger than 200 meters across are multicomponent structures or rubble piles—agrees with recent computer modeling of collisions, which also finds a transition at that diameter. A collision can blast a large asteroid to bits, but after the collision those bits will usually move slower than their mutual escape velocity . Over several hours, gravity will reassemble all but the fastest pieces into a rubble pile. Because collisions among asteroids are relatively frequent, most large bodies have already suffered this fate. Conversely, most small asteroids should be monolithic, because impact fragments easily escape their feeble gravity.
Ques. 1/4
The passage implies which of the following about the five asteroids mentioned in line 12?
Solution
1. Passage Analysis:
Progressive Passage Analysis
| Text from Passage | Analysis |
|---|---|
| When asteroids collide, some collisions cause an asteroid to spin faster; others slow it down. | What it says: Sometimes asteroid crashes make them spin faster, sometimes slower What it does: Sets up basic background - asteroid collisions affect rotation Source/Type: Statement of fact about asteroid behavior Connection to Previous Sentences: This is our opening - no previous context to connect to Visualization: Collision Type A: Asteroid spinning at 5 hours per rotation → hits something → now spinning at 3 hours per rotation (faster) Collision Type B: Asteroid spinning at 2 hours per rotation → hits something → now spinning at 4 hours per rotation (slower) What We Know So Far: Asteroid collisions change rotation speeds in both directions What We Don't Know Yet: Why this matters, what patterns this creates Reading Strategy Insight: Simple opening concept - just establishing that collisions affect spin rates |
| If asteroids are all monoliths—single rocks—undergoing random collisions, a graph of their rotation rates should show a bell-shaped distribution with statistical \"tails\" of very fast and very slow rotators. | What it says: If asteroids are solid rocks getting hit randomly, we'd expect a normal distribution with some very fast and very slow spinners at the extremes What it does: Introduces first hypothesis and its predicted outcome Source/Type: Theoretical prediction (\"should show\") Connection to Previous Sentences: - Sentence 1 told us: Collisions change rotation speeds - NOW Sentence 2: Explains what pattern we'd expect if asteroids are solid rocks This builds on the collision concept by predicting outcomes Visualization: Bell curve graph: Left tail: Very slow rotators (24+ hours per rotation) Middle peak: Average rotators (8-12 hours per rotation) ← Most asteroids here Right tail: Very fast rotators (1-2 hours per rotation) What We Know So Far: Solid rock asteroids + random collisions = bell curve of rotation speeds What We Don't Know Yet: Whether this is actually what we observe Reading Strategy Insight: This is setting up a prediction to test - watch for whether reality matches this expectation |
| If asteroids are rubble piles, however, the tail representing the very fast rotators would be missing, because any loose aggregate spinning faster than once every few hours (depending on the asteroid's bulk density) would fly apart. | What it says: If asteroids are loose rock piles instead, the very fast spinners would be missing because they'd break apart from spinning too fast What it does: Introduces alternative hypothesis and its different predicted outcome Source/Type: Theoretical prediction with physical reasoning Connection to Previous Sentences: - Sentence 2 told us: Solid rocks would show a complete bell curve - NOW Sentence 3: Contrasts this - loose piles would show an incomplete bell curve This gives us two competing predictions to test Visualization: Modified bell curve graph: Left tail: Very slow rotators (24+ hours per rotation) ✓ Present Middle peak: Average rotators (8-12 hours per rotation) ✓ Present Right tail: Very fast rotators (1-2 hours per rotation) ✗ MISSING - they flew apart! What We Know So Far: • Solid asteroids = complete bell curve • Rubble pile asteroids = bell curve missing fast rotators What We Don't Know Yet: Which pattern matches real observations Reading Strategy Insight: Now we have two clear, competing predictions - the next logical step is to see which one matches reality |
| Researchers have discovered that all but five observed asteroids obey a strict limit on rate of rotation. | What it says: Scientists found that almost all asteroids (except 5) have a maximum spin speed they don't exceed What it does: Provides the key observational evidence that will resolve our two hypotheses Source/Type: Research findings (\"researchers have discovered\") Connection to Previous Sentences: - Sentence 2 predicted: Solid rocks would have very fast rotators - Sentence 3 predicted: Rubble piles would be missing very fast rotators - NOW Sentence 4: Gives us the actual data - almost no very fast rotators exist! This strongly supports the rubble pile hypothesis Visualization: Reality check: Total asteroids observed: Let's say 1000 Asteroids that spin faster than the limit: Only 5 Asteroids that obey the speed limit: 995 This matches the \"missing right tail\" prediction from rubble piles! What We Know So Far: • Real data shows almost no very fast rotators • This supports rubble pile hypothesis over solid rock hypothesis What We Don't Know Yet: Details about those 5 exceptions Reading Strategy Insight: Key moment - the data clearly favors one hypothesis over the other |
| The exceptions are all smaller than 200 meters in diameter, with an abrupt cutoff for asteroids larger than that. | What it says: Those 5 fast-spinning asteroids are all small (under 200 meters), and no asteroid bigger than 200 meters spins fast What it does: Provides crucial detail about the exceptions that will lead to the main conclusion Source/Type: Detailed research findings Connection to Previous Sentences: - Sentence 4 told us: 5 asteroids break the speed limit - NOW Sentence 5: Tells us these exceptions are all small, with a clear size cutoff This adds important nuance - size matters for the speed limit Visualization: Size vs Speed Pattern: Asteroids under 200m: Can spin fast (5 examples exist) Asteroids over 200m: Cannot spin fast (0 examples, strict cutoff) 200m diameter ← This is our critical threshold What We Know So Far: • Large asteroids (200m+) = always slow rotation (rubble piles) • Small asteroids (<200m) = can rotate fast (possibly solid) What We Don't Know Yet: Why 200m is the magic number Reading Strategy Insight: The pattern is getting clearer - size determines structure and rotation capability |
| The evident conclusion—that asteroids larger than 200 meters across are multicomponent structures or rubble piles—agrees with recent computer modeling of collisions, which also finds a transition at that diameter. | What it says: The obvious conclusion is that big asteroids are rubble piles, and computer simulations support this with the same 200-meter cutoff What it does: States the main conclusion and provides supporting evidence from modeling Source/Type: Author's conclusion (\"evident conclusion\") plus computer modeling support Connection to Previous Sentences: - Sentences 2-5 built up: Theoretical predictions → Real data → Size pattern - NOW Sentence 6: Gives us the simple takeaway + confirming evidence This is NOT new complexity - it's the logical conclusion we've been building toward Visualization: Evidence Convergence: Real asteroid data: 200m cutoff for fast rotation Computer simulations: 200m cutoff for structure change Both point to: Large = rubble piles, Small = can be solid What We Know So Far: • Large asteroids are rubble piles (confirmed by data + modeling) • 200m is the critical size threshold What We Don't Know Yet: The physical mechanism behind this pattern Reading Strategy Insight: Feel confident here - this is the payoff sentence that resolves our earlier questions |
| A collision can blast a large asteroid to bits, but after the collision those bits will usually move slower than their mutual escape velocity . | What it says: When a big asteroid gets smashed, the pieces usually don't fly away completely because they're not moving fast enough to escape each other's gravity What it does: Begins explaining the physical mechanism behind the rubble pile formation Source/Type: Physical explanation of collision dynamics Connection to Previous Sentences: - Sentence 6 concluded: Large asteroids are rubble piles - NOW Sentence 7: Starts explaining HOW they become rubble piles This elaborates on the conclusion by providing the underlying physics Visualization: Collision Aftermath: Large asteroid gets hit → breaks into chunks Chunk speeds after impact: 50 meters/second Escape velocity needed: 100 meters/second Result: Chunks stay in the area (too slow to escape) What We Know So Far: • Large asteroids become rubble piles when hit • The pieces usually don't fly away completely What We Don't Know Yet: What happens to those pieces next Reading Strategy Insight: This is starting the \"how it works\" explanation - building on our established conclusion |
| Over several hours, gravity will reassemble all but the fastest pieces into a rubble pile. | What it says: Within hours, gravity pulls most of those pieces back together into a loose collection What it does: Completes the explanation of how rubble piles form Source/Type: Physical process description Connection to Previous Sentences: - Sentence 7 told us: Collision pieces usually don't escape - NOW Sentence 8: Completes the story - gravity reassembles them This finishes the step-by-step process: collision → pieces → reassembly → rubble pile Visualization: Rubble Pile Formation Timeline: Hour 0: Big solid asteroid gets hit, breaks apart Hour 1-6: Pieces drift in space but stay nearby Hour 6+: Gravity pulls pieces back together Final result: Loose rubble pile instead of solid rock What We Know So Far: • Complete mechanism: collision → breakup → gravitational reassembly → rubble pile • This explains why large asteroids are multicomponent structures What We Don't Know Yet: Why this applies more to large asteroids than small ones Reading Strategy Insight: The mechanism is now complete - this explains our earlier observations |
| Because collisions among asteroids are relatively frequent, most large bodies have already suffered this fate. | What it says: Since asteroid crashes happen often, most big asteroids have already been through this break-apart-and-reassemble process What it does: Explains why the rubble pile pattern is so common among large asteroids Source/Type: Logical inference based on collision frequency Connection to Previous Sentences: - Sentences 7-8 explained: How one collision creates a rubble pile - NOW Sentence 9: Explains why this pattern dominates - collisions are frequent This shows why our observational data (mostly slow rotators) makes sense Visualization: Large Asteroid Population Over Time: Originally solid large asteroids: 100% After millions of years of frequent collisions: Still solid: ~5% Now rubble piles: ~95% This matches our observation of very few fast rotators! What We Know So Far: • Mechanism explains individual cases • Frequency explains why pattern dominates large asteroid population What We Don't Know Yet: Why small asteroids might be different Reading Strategy Insight: This connects our physical mechanism back to our original observations - everything is fitting together |
| Conversely, most small asteroids should be monolithic, because impact fragments easily escape their feeble gravity. | What it says: On the flip side, small asteroids should stay as solid rocks because their weak gravity can't hold impact pieces together What it does: Explains the other side of the size pattern and completes the full picture Source/Type: Logical conclusion (\"should be\") based on gravitational principles Connection to Previous Sentences: - Sentences 7-9 explained: Why large asteroids become rubble piles - NOW Sentence 10: Explains why small asteroids stay solid This completes our understanding of the 200m cutoff - it's about gravitational strength Visualization: Small vs Large Asteroid Collision Outcomes: Small asteroid (under 200m) gets hit: → Pieces move faster than escape velocity → Pieces fly away permanently → Remaining core stays solid Large asteroid (over 200m) gets hit: → Pieces move slower than escape velocity → Pieces reassemble via gravity → Becomes rubble pile What We Know So Far: • Complete picture: Size determines post-collision structure • Large = strong gravity = rubble piles = slow rotation • Small = weak gravity = stay solid = can rotate fast What We Don't Know Yet: Nothing major - the explanation is complete Reading Strategy Insight: Final piece of the puzzle - now everything makes perfect sense! The passage has given us a complete, coherent explanation that connects all our original observations. |
2. Passage Summary:
Author's Purpose:
To explain how scientists figured out the internal structure of asteroids by studying their rotation patterns and then provide the physical mechanism behind these patterns.
Summary of Passage Structure:
In this passage, the author builds their explanation through a clear scientific investigation:
- First, the author sets up two competing theories about asteroid structure - either they're solid rocks or loose piles of rubble - and explains what rotation patterns each theory would predict.
- Next, the author reveals the actual observational data showing that almost all asteroids follow a strict speed limit, with only five exceptions that are all smaller than 200 meters.
- Then, the author draws the obvious conclusion that large asteroids are rubble piles while small ones can be solid, and notes that computer models support this same size cutoff.
- Finally, the author explains the physical process behind this pattern - when large asteroids get hit, the pieces reassemble due to gravity, but small asteroids lose their pieces because their gravity is too weak to hold them.
Main Point:
Large asteroids (over 200 meters) are loose collections of rubble held together by gravity, while small asteroids tend to be solid rocks, and this difference explains why we see very few fast-spinning large asteroids in space.
1. Question Analysis:
The question asks what the passage implies about the five exceptional asteroids mentioned in line 12. These are the asteroids that don't \"obey a strict limit on rate of rotation\" - meaning they spin faster than the speed limit that applies to almost all other observed asteroids.
Connecting to Our Passage Analysis:
From our analysis, we know:
- The passage establishes two competing theories: asteroids are either solid rocks (monoliths) or loose piles (rubble piles)
- Solid rocks can spin very fast, while rubble piles would fly apart if they spun too fast
- The observational data shows almost all asteroids follow a strict speed limit (supporting the rubble pile theory)
- The five exceptions are all smaller than 200 meters in diameter
- The passage concludes that large asteroids are rubble piles, while \"most small asteroids should be monolithic\"
Prethinking:
Since these five asteroids are the only ones that can spin faster than the speed limit, and the passage explains that only solid structures can maintain fast rotation (because loose rubble piles would fly apart), these five exceptions must be monoliths. The passage directly supports this by noting that \"most small asteroids should be monolithic\" and all five exceptions are small (under 200 meters). The ability to spin fast without flying apart is the key indicator that distinguishes solid asteroids from rubble piles.
Answer Choices Explained
A
Their rotation rates are approximately the same.
Why It's Wrong:
- The passage tells us these asteroids all spin faster than the speed limit, but doesn't specify their exact rotation rates
- Being exceptions to the same limit doesn't mean they have the same rotation rate
- The passage focuses on the fact that they CAN spin fast, not on their specific speeds
Common Student Mistakes:
- Don't all "fast rotators" spin at similar speeds? → No, the passage only tells us they exceed the speed limit, not that they're similar to each other
- If they're all exceptions, aren't they all the same? → They share the characteristic of being able to spin fast, but this doesn't mean identical rotation rates
B
They have undergone approximately the same number of collisions.
Why It's Wrong:
- The passage doesn't provide any information about collision frequency for these specific asteroids
- The passage mentions collision frequency in general terms for large asteroids, not these small exceptions
- There's no basis in the text to infer anything about their collision history
Common Student Mistakes:
- Don't all asteroids experience similar collision rates? → The passage doesn't give us data to compare collision histories
- Since they're all small, haven't they all avoided major collisions? → This assumes facts not stated in the passage
C
They are monoliths.
Why It's Right:
- The five asteroids are the only ones that can spin faster than the strict speed limit
- The passage explains that only solid structures can maintain fast rotation because loose aggregates "would fly apart"
- These asteroids are all small (under 200 meters), and the passage states "most small asteroids should be monolithic"
- Their ability to spin fast without disintegrating is direct evidence of solid, single-rock structure
Key Evidence: "most small asteroids should be monolithic, because impact fragments easily escape their feeble gravity"
D
They are composed of fragments that have escaped the gravity of larger asteroids.
Why It's Wrong:
- This reverses the relationship described in the passage
- The passage explains that small asteroids stay monolithic because fragments escape their gravity
- These five asteroids are the small ones that retained their solid structure, not fragments that escaped
- The passage describes fragments escaping FROM asteroids, not becoming independent asteroids themselves
Common Student Mistakes:
- Are small asteroids fragments from larger ones? → The passage suggests small asteroids lose fragments, not that they are fragments
- Don't all small space rocks come from bigger asteroids breaking up? → The passage doesn't support this origin story for the five exceptions
E
They were detected only recently.
Why It's Wrong:
- The passage gives no information about when these asteroids were discovered
- The timing of their detection is irrelevant to the scientific argument being made
- The passage focuses on their physical properties (size, rotation rate, structure), not discovery dates
Common Student Mistakes:
- Since they're exceptions, were they recently found? → The passage doesn't connect exceptional properties to discovery timing
- Don't new discoveries usually involve unusual objects? → This assumes information not provided in the passage
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