homework help > physics > physics q&a board > topic: thank you for help...

Q BgQuestion:

      
Rookie
Karma Points: 0
Respect (86%):
posted by  xibai on 11/5/2009 12:15:19 AM  |  status: Closed  |  Earned Karma: 0

Thank you for help

Course Textbook Chapter Problem Needs by
N/A N/A 12 43P 11/4/2009 at 11:00:00 PM
Question Details:
(a) Calculate the gravitational potential energy of a 6.6 kg mass on the surface of the Earth.
J

(b) Calculate the gravitational potential energy at an altitude of 385 km.
J

(c) Take the difference between the results for parts (b) and (a), and then compare with mgh, where h = 385 km. (Do not round your intermediate results!)
J (difference between parts a and b)
J (mgh)
Tags: Physics

cRequests for Clarification:

Scholar
Karma Points: 306
posted by Martha1966 on 11/5/2009 11:23:36 AM  |  status: Live
Clarification Details:
What is it about the answer that you did not find helpful?
"Reality is merely an illusion, albeit a very persistant one." -Albert Einstein
Rookie
Karma Points: 0
posted by xibai on 11/6/2009 2:29:35 AM  |  status: Live
Clarification Details:
How about the (b)? I dont how to figure out. I get answer-2.5e+7. it saids i have the wrong orders of magnitude.

AAnswers:

Answer Question Ask for clarification
Scholar
Karma Points: 306
posted by Martha1966 on 11/5/2009 2:43:32 AM  |  status: Live
Asker's Rating: Lifesaver   
Response Details:
"Reality is merely an illusion, albeit a very persistant one." -Albert Einstein
Scholar
Karma Points: 306
posted by Martha1966 on 11/6/2009 1:32:56 AM  |  status: Live
Asker's Rating: Helpful   
Response Details:
OK, just so we are clear.
Gravitational PE is mass*gravity acceleration*height, or mgh. If you take upward as positive, gravity acceleration would be -9.81 m/s2. Maybe your book convention is different, but I assure you, I know my Physics.
When they ask you to take the difference, all you have to do is subtract the two numbers. Again because your book convention might be different, you may be playing around a bit with the addition and subtraction of negative numbers, but that is really all they are asking.
So since I took up as positive, the difference between a and b would be 0J-(-2.49x107)J, and that would result in 2.49x107J.
"Reality is merely an illusion, albeit a very persistant one." -Albert Einstein
Scholar
Karma Points: 306
posted by Martha1966 on 11/7/2009 3:10:34 PM  |  status: Live
Asker's Rating: Helpful   
Response Details:
Orders of magnitude deal with the results as exponential powers of 10. For example, if I were to say that the force applied by some a weight is 45kN, then the order of magnitude would be 104 N.
I am not sure what form your college or high school would like the answer to be in. However, you should be able to answer the problem using the example above as a guide.
"Reality is merely an illusion, albeit a very persistant one." -Albert Einstein
Answer Question Ask for clarificarion
Ask New Question

Join Cramster's Community

Cramster.com brings together students, educators and subject enthusiasts in an online study community. With around-the-clock expert help and a community of over 100,000 knowledgeable members, you can find the help you need, whenever you need it. Join for free today » How Cramster is different from tutoring »

Need Help In

Useful Links