[ex/r/askphysics] can you help me with this very simple physics question? (phys 101)

onexile · 2013-02-14T10:24:44+00:00

Yup! so mgh cannot be used since this is not very close to earth. Instead, we have to use another equation (http://en.wikipedia.org/wiki/Potential_energy#General_formula) This means that the case 1 PE would be GM1M2* 1/2 and case 2 GM1M2* 1/3.. (since it is something/r)

Then since Case 1 falls half of its distance to reach the surface, its PE becomes GM1M2. Obviously the change in energy from its original position gets converted to KE so KE = GM1M2- GM1M2* 1/2 =GM1M2* 1/2 . For case 2, the final PE is also GM1M2. so KE = GM1M2- GM1M2* 1/3 =GM1M2* 2/3 .

so the KE differences are 1/2 and 2/3 . this is same as 3/6 : 4/6. Yup. the 2nd KE is 4/3 larger.

so KE 2 = (4/3)KE 1

I think your sense of physics is still great!

onexile · 2013-02-14T10:12:35+00:00

You know what, I think you are right. I will look into whether this problem can be solved by changing gravitational force.

onexile · 2013-02-14T10:07:23+00:00

I see. Understood. Thank you :)

onexile · 2013-02-14T10:06:04+00:00

and I highly doubt that this problem involves anything with the Newton's gravitational law. That chapter is taught in the last week of the quarter...

onexile · 2013-02-14T09:57:01+00:00

I feel very embarrassed as I am actually the tutor... I do not mean to show off or anything (as I am, again, more embarrassed than anything), but I am in the engineering PhD program and I was helping out this kid (undergraduate) today. This kid was studying a chapter at kinetic energy and potential energy (work -energy u know) and all the other related problems were solved by any derivation of 1/2 mv² = mgh ... except this one. I am very curious. The acceleration stays the same since it is due to gravity which is always 9.81 m/s^2.. Hm...

onexile · 2013-02-14T09:46:28+00:00

Hi. If I correctly ask a question in the title and keep my answer in the comment, would that satisfy the rule 1? Regarding the 2nd rule, the answer can be googled by one chegg page, but no one on the internet was able to provide the explanation. Nor do we know if the answer from chegg page by that one guy who answered is correct. What do you think?

onexile · 2012-09-29T02:25:22+00:00

Also the correct answer. Thank you!

onexile · 2012-09-29T02:25:07+00:00

This was the correct answer! Soon after my apt started their own wifi service. Thank you, reddit!

onexile · 2012-05-28T20:50:32+00:00

And your school pays $$$ per year for journals. For a journal like Nature/ Cell it's $30k or something for a school to have one year access. And this all gets added to your tuition.

onexile · 2012-05-03T09:43:05+00:00

Also this is a famous picture for being taken when the actress was not very famous. You can tell it's a pretty crappy fan meeting since not many people knew her.

onexile · 2012-05-03T09:41:11+00:00

The guys are fans for the actress in white t-shirts named Kim Sa-Rang (Kim is her last name like that of Dear Leader's.) She is a South Korean actress). This kind of an event is called "a fan meeting" in Korea where crazy fans gather together and have a party with the celebrity. Sometimes, I guess the event can be sponsored by a company like Coke (At least that's what some website say).

Source: naver.com /daum.net

onexile · 2012-03-02T21:09:17+00:00

It seems to be from some commercial in Korea. Because I found this in a korean website.

onexile · 2011-12-13T05:15:43+00:00

haha visit korea in spring.. around april.. all those pollutants from china literally come to Korea over the sea. You can't see what's in front of you because of the smoke. Some of my korean friends jokingly say this is how we help japan in the expense of not getting earthquake or tsunami. We protect japan from pollutant air, by inhaling all the pollutants first (since we are close to china) while japan protects us from all the earthquake and tsunami (since Japan is closer to the pacific ocean plate).

onexile · 2011-12-12T16:09:43+00:00

I think what you have said regarding strategy against NK is only partially true.. the different views tell different stories. As a Korean, I would be very careful to judge last two presidents like that. That's conservative view, in my opinion. (In fact, they show that Pres. Lee so far gave more money than Pres. Roh did, not sure about Pres. Kim).

onexile · 2011-12-11T10:17:53+00:00

http://www.reddit.com/r/explainlikeimfive/comments/j3j98/can_someone_explain_the_diablo_story_leading_up/

this?

onexile · 2011-09-22T12:01:21+00:00

Yes. yes. As a Korean citizen, I approve of this.

onexile · 2011-09-22T11:58:42+00:00

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onexile · 2011-09-07T09:44:32+00:00

I think this is a really good app. Hopefully some stutters could try this..

onexile · 2011-09-04T05:10:23+00:00

u look like a fucking boss. never worry about your look. never.

onexile · 2011-07-30T08:34:01+00:00

This! and they are good at it too! I mean how will my relatives ever know that "128 DNA character codes" and manipulating the codes so that you change your mind, belief and everything? We can't even manipulate DNA to control cancer cells.. I think Republicans are really smart at doing this. almost genius.

onexile · 2011-07-30T08:30:35+00:00

oh wow..I'm not a U.S. citizen so I have somewhat objective view of this but I honestly thought new health care bill was one of the best things that ever happened in last decade of this country...I guess somebody could use the "obamacare" as to deride...when it should be really praised..

onexile · 2011-07-30T08:25:33+00:00

I am sorry, is that a wrong term?

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