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Author Topic: gravitation doubt...  (Read 745 times)

Offline helllife

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gravitation doubt...
« on: January 29, 2010, 03:30:48 pm »
1)An object projected at 127m/s upward from a small moon reaches a height of 5.03 km. If the radius of the moon is 1820km, calculate its mass.

i just dnt knw how to work it out...can  anyone please tell me the answer and shows the working? i would appreciated if anyone do so.
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Offline astarmathsandphysics

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Re: gravitation doubt...
« Reply #1 on: January 29, 2010, 03:41:21 pm »
I will do it when I get home
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Offline astarmathsandphysics

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Re: gravitation doubt...
« Reply #2 on: January 30, 2010, 12:43:39 pm »
1)An object projected at 127m/s upward from a small moon reaches a height of 5.03 km. If the radius of the moon is 1820km, calculate its mass.
KE=increase in GPE
1/2mv^2=GMm(1/r1-1/r2)
m cancels to gicve 1/2v^2=GM(1/r1-1/r2)
1/2*127^2=6.67*10^-11*M*(1/(1820000)-1/(182000+5030))=M*1.01*10^-19
M=8064.5/1.01*10^-19 =7.98*10^22 kg
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Offline helllife

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Re: gravitation doubt...
« Reply #3 on: January 30, 2010, 04:28:42 pm »
thank you!!!

i may ask some more question later on..... :)
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Offline astarmathsandphysics

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Re: gravitation doubt...
« Reply #4 on: January 30, 2010, 05:00:38 pm »
If I can make a topic out of it I might make a page on my website
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