BFMracing

General Category => General Board => Homework Haven => Topic started by: -Ajax- on October 24, 2010, 04:07:28 AM

Title: What if...
Post by: -Ajax- on October 24, 2010, 04:07:28 AM
In one of my physics lessons...
we had a question that said "if you remove 1% of the electrons from each of two 60kg students standing 1 metre apart, what would the FORCE on each of them be? assume humans are 100% water"

we got some crazy force in the order of x10^25  and then an acceleration (using F=ma) of about 1.5x10^23 ms^-2.
My question is how many 60kg students would we need to fire towards the sun to push the earth out of orbit? lol

PS. the first part is what we did in the lesson, the 2nd part (about moving the earth) is me being theoretical lol
Title: Re: What if...
Post by: TUR80 on November 10, 2010, 08:23:27 PM
gosh our phisics has got boring recently
i think it is da teacher
Title: Re: What if...
Post by: jim360 on November 11, 2010, 02:11:11 AM
I think in order to answer the second question you'd have to suspend disbelief for a second. Any student or mass with such charge would have a huge potential difference relative to Earth, so I would not be surprised if it very quickly discharged (because the electrons in earth would "want" to flow back to the student) and returned to neutral. Which among other things is why we get lightning.

I know that sounds a bit pedantic but then, on the other hand, you'd probably have found that we should have left the Sun's orbit a long time ago if there was such a concentrated charge allowed to attract the Earth to it over a long period of time. Such as a cloud.

So, suspending disbelief:

The gravitational force on the Earth due the the Sun is approximately 3*1022 Newtons. So, basically, because in fact this is tiny in comparison the to electrical forces due the the students, it would likely take only one student to escape from Earth's gravity, and the reactive force would be many times large enough.

Probably.

Title: Re: What if...
Post by: -Ajax- on November 12, 2010, 10:14:25 AM
Lol thanks Three60 :)
was just throwing it out there to see if there was an answer