Planetary Dynamics
Question:

4 People tried to answer this question

Great!

Now you are ready for the MIT BLOSSOMS video lecture on Galaxies and Dark Matter, found in the following link:

http://blossoms.mit.edu/videos/lessons/galaxies_and_dark_matter

Oops!

You accidentally chose the wrong answer.

That is incorrect.

Think about the relation between the orbital period and the radius.

Try again.

Notice how the velocity should change with the distance from the Sun.



Comments:
1.  rozenblum yael (25.06.2017 pm 12.13.33)
Colleague evaluation

Itamar,

I find this question to be very interesting.

Your use of animations in the answers was excellent and each animation you chose was different and related to another mistake. For example, one option related to the principle of changing velocity with distance, and another possibility related to the ratio of orbitals.

I really liked your reference to the wrong answers. You did not write to the student why it was a mistake, but you made him pay attention to a scientific principle such as the change of the radius and its effect on speed. In my opinion this is the right way to develop a higher level of thinking, since the student must understand why he was wrong.

However, in one of the options you wrote that: "you accidentally chose the wrong answer". From such a remark, the student can not learn anything and will probably guess the correct answer.

Based on the information you gave I didn't succeeded to answer your question, so I think you should gave more information about the topic. For example: You used formulas in a question, but you did not explain when to use them. In my opinion, it is necessary to present an example question with a complete solution that demonstrates how and when to use the formulas.

In addition, as I understand, the question does not include calculation, because there is no numerical data in the question. Therefore, the formulas you attached to the question illustrate the principle. (dependence on radius, mass). Although you have wrote what each element in the formula, which makes it easier to understand. But it is important to understand that for a student who is not familiar with the subject and does not have a background in physics, the formulas are unclear and not sure that he will be able to answer the question. Therefore, it is worth adding a literal explanation to the formulas, or use video or animation that explains the formula.

You Added a link to the Blossoms lecture at the end of the question and write that this is a question to prepare for Blossoms related lecture. In my opinion, the question as it is written today is not appropriate to be a preparation question. In order for this question to be a preparation question, you should add explanations and more detailed information about the subject and the concepts you specify. For example, you wrote that the subject of the question is planetary dynamics, but you did not explain what it is, or you indicated the term "centrifugal force" but did not give an explanation of the power except that it acts in a circular motion.

In conclusion, I think that the subject you have chosen is fascinating and the depth of the question creates interest and curiosity. However, you need to add information about the subject so that even students who do not know it can answer the question.

yael. 



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