QUESTION TEXT: A ring of gas emitting X-rays flickering…
QUESTION TYPE: Most Strongly Supported
FACTS:
- A gas ring flickers 450 times per second. It is orbiting a black hole.
- According to widely accepted theory, this means that the gas ring must be 49 km in diameter.
- If this is so, the black hole must be spinning.
ANALYSIS: The question stem actually adds an additional fact: assume the theories are correct.
That makes things easy. If the theories are correct, then the black hole must be spinning.
___________
- We don’t care about black holes with gas rings of other diameters. We only care about this black hole, and gas rings with diameters of 49 km.
- What a silly answer. We have no idea what things emit flickering X-rays. Maybe those X-rays are really common! Maybe humans emit flickering X-rays. Who knows?
- CORRECT. If the theories are correct, the only way for the ring to be stable at 49 km is for the black hole to be spinning.
- We have no info about why a black hole spins. We only care about whether it spins.
- Same as B. There could be a million reasons why a black hole is stationary. We have no evidence for this answer.
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