QUESTION TEXT: Rocket engines are most effective when exhaust…
QUESTION TYPE: Necessary Assumption
CONCLUSION: Rockets need long and short nozzles for their ascents.
REASONING: At low altitudes, rockets need short nozzles. In the upper atmosphere, rockets need long nozzles.
ANALYSIS: This already sounds like a good argument. But, you know this is flawed. So how could this be wrong? Well, what if some rockets only make short ascents. Maybe some rockets never hit high altitudes. In which case they would only need short nozzles.
So the argument is assuming that every rocket goes high enough to hit the thin upper atmosphere.
(You may have thought that all rockets are space rockets. Nope. Some rockets, such as ICBMs, never leave the atmosphere. All missiles are rockets.)
- It doesn’t matter how difficult it is to equip nozzles. The argument is only about whether rockets need both nozzles.
- CORRECT. If this isn’t true, then not all rockets need long nozzles.
Negation: Some rockets don’t pass through the thin upper atmosphere.
- The argument says rockets need both nozzles to be are most effective. But a rocket might be able to reach high altitudes even if it’s not fully effective.
Negation: Less than effective rockets can still reach high altitudes even with only short nozzles.
- This is an absurd answer. Absurd answers are almost never correct. Rockets only have two types of nozzle, and air pressure changes constantly as you rise in the atmosphere. So it’s impossible to match pressure exactly through ascent.
Also, this answer talks about working effectively. The stimulus is about what’s required to work most effectively. Those are two very different things.
I worked effectively today, but I could have been far more effective.
- This isn’t necessary. The argument only said the engines need long and short nozzles. It’s possible these could be on separate engines.
Negation: A rocket can be most effective if it has zero engines with long and short, as long as there are some engines with long and some engines with short.
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