#25 - According to the Newtonian theory of gravity, the gravitational force

[Administrator]

Complete Question Explanation

Justify the Conclusion. The correct answer choice is (B).

Answer choice (A):

Answer choice (B): This is the correct answer choice.

Answer choice (C):

Answer choice (D):

Answer choice (E):

This explanation is still in progress. Please post any questions below!

[Claire.L]

Hello!

Could you please explain why B is correct and the others are incorrect? I don't understand this question. Thank you!

[Dana D]

Hey Claire,

We are told that according to the Newtonian theory of gravity, gravitational force = about mass and distance between bodies. Newtonian theory does not care about what the bodies are made of. To calculate orbits, Newtonian theory does not care about the structure and constitution of the Sun or other planets (this would be "what they're made of) to calculate orbit.

In justify questions such as this, you want to key in when the stimulus is talking about two different ideas in the premise and conclusion. Here, the premise talks about gravitational force in the premise, but then draws a conclusion about calculating orbit. In order to make that jump, we need an answer choice that will connect those ideas together.

Answer (B) talks about both planetary orbits and gravitational forces, so right away it looks like a strong contender. Then, considering the content of it, Answer (B) is saying that in order to calculate orbit according to Newtonian theory, all you have to care about is their gravitational forces, which we know based on the first sentence of the stimulus means just their mass and the distance between them. So, if we added the information in answer (B) into the stimulus, it would make sense for us to conclude that in order to calculate the orbit of plants, we don't care about what they are made of, we just care about their mass and the distance between them (their gravitational forces).

Hope that helps!

[lemonade42]

Can you explain why D is wrong? My prephrase was that "determining mass might involve more than just the structure and constitution". So we need to show that those 2 factors are the only two things to show mass, so then you can conclude you don't need them because we don't need mass. I understand how B is correct, but I feel like we still need to establish D as well?

[Jeff Wren]

Hi lemonade,

I think that you may be having trouble with the premise, which is throwing off your prephrase.

The premise tells us that all you need to determine gravitational force is knowing the mass and distance between two objects, which is independent of what the objects are made of. In other words, you don't need to know the structure and the constitution of the objects (structure and constitution are descriptions of what the objects are made of.)

We don't know how the mass and distance between the objects is determined, but that's not the part that is missing in this argument.

What we need to do to justify this argument is to link the new information in the conclusion (about calculating their orbits) back to the premise (about gravitational forces).

If you add Answer B into the argument just before the conclusion, it perfectly closes the gap in the logic and justifies the argument.

Premise: According to Newtonian theory of gravity, gravitational force only depends on mass and distance, not what the objects are made of.

Answer B: According to Newtonian theory, to calculate orbits, you only need their gravitational forces.

Conclusion: According to Newtonian theory, to calculate their orbits, you don't need to know what the objects are made of.