Tuesday, September 28, 2010
Ch6_3 #3
See Ch6 Sheet 24 for the exact expression of the Gravitational Potential Energy. Use it to calculate the change in potential energy, the difference in potential energy for the 2 positions. Compare this with mgh, which is an approximate change of the potential energy neglecting the variation of g along the path of the object (See Ch 6 Sheet 24').
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11 comments:
" ...to a height of 900kg" ?
it should be "to a height of 900km". I used 900km instead of 900kg,then I got the right answer.
i cannot seem to get this right...
[(GmM/r)exact-(mgh)approx.]/(GmM/r)exact
is that how to set this up to find the relative error?
Yes, although it could also be (approx-exact)/exact
But for exact calculation, you need to use the *difference* between the potentials for the two positions, as stated in the problem. For the approximate, in the expression mgh, h is the height relative to the starting position
I'm having trouble too. Can you use the height relative to the ground for both the approximation and exact formula? Because when I do that and calculate the relative error it gives a value of 0.30 which isn't the right answer.
I am really unable to solve this problem as well. I set it up as [(GmM/r)exact-(mgh)approx.]/(GmM/r)exact....in which r=radius of the earth + h. I cant seem to get this right.
i did everything that these comments say to do but i cant get the right answer. can someone help me
plz help!! the comments arent working out for me
Please help. We only have an hour left.
use (GM/r(actual)-gh(approx)/(GM/r)
make sure that you convert h to meters.
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