Thermodynamics is concerned with changes in the properties of matter

3. Given the context, what is the meaning of the highlighted phrase?

Explanation

The key contrast to make note of here is the difference between “manifestation” and “statement”—that is, the difference between an appearance of something and a declaration of it. What the highlighted phrase, then, says is that the motion of the piston is an appearance—an example, if you will—of the second law of thermodynamics but it is not an explanation or proof of it.

Choice (A) you can reject because a universal law is not applicable only to certain circumstances.

While (B) might suggest an excellent example to demonstrate the second law of thermodynamics, it is not proof of it—(B) is, in fact, the opposite of our desired answer; furthermore, it would be a poorly worded answer in that it suggests the second law of thermodynamics relates to the physical object of the piston rather than the gas within the cylinder.

(C) is also inaccurate because the highlighted phrase tells us that the change in heat in the cylinder is an example of the second law of thermodynamics.

Answer choice (D), however, states that the change in heat is an example rather than a proof of the second law of thermodynamics, and this is the correct answer.

Finally, since the highlighted phrase refers to an example of the second law of thermodynamics, it certainly doesn’t disprove that law, so (E) is wrong.

Answer: D

1. The scope of this passage is

Explanation

Remember, the first thing to do with any passage is to identify the topic and the scope. The topic is the broad subject of the passage—in this case “thermodynamics.” You can immediately rule out (D) because it speaks of the topic rather than the scope. The scope of the passage focuses on the application of thermodynamics to the motion of a piston, which is what answer choice (A) states—it is the correct answer.

Choices (B), (C), and (E) refer to specific subjects mentioned in the passage but do not refer to the passage as a whole.

Answer: A

2. Based on this passage, if we were to record the temperature of the gas within a cylinder of a car engine when we were driving the car at 20 mph, and measure it again after accelerating the car to 40 mph (thus speeding up the piston), what would we expect to find?

Explanation

The passage informs you that the faster a piston is moving in and out of a cylinder, the hotter the gas will become. Based on this, you can infer that the when the car is moving faster, the gas will become hotter because the pistons will be moving more quickly. Thus, the correct answer choice is (B). Even if you are unsure of the concepts described in a passage, sometimes you can make a reasonable guess at an answer based on common sense. In this case, you can assume that the parts of a car’s engine will be hotter when the car is going faster without having to apply what you have learned in the passage about thermodynamics.

Answer: B