Gravitational Potential Energy (Multiple Choice Question)

[McAfee]

Homework Statement

Question:
Rank the paths according to the corresponding change in the gravitational potential energy of the rocket–moon system, greatest first.

A. 1 > 3 > 5 > 2 = 4 = 6
B. 2 = 4 = 6 > 5 > 3 > 1
C. 1 = 2 = 3 = 4 = 5 = 6
D. 1 > 2 = 4 = 6 > 3 > 5

The Attempt at a Solution

I'm not understanding the question. I guess it would be A, but I'm not sure why.

 

[Delphi51]

Probably "1>3" means orbit 1's energy is greater than orbit 3's energy.

 

[McAfee]

Probably "1>3" means orbit 1's energy is greater than orbit 3's energy.

Sorry I forgot to include the question.

 

[Delphi51]

That "changes" things! It must mean the change going from a to b. Potential energy only. Much easier. You will want to have your formula for grav potential energy handy.

 

[McAfee]

That "changes" things! It must mean the change going from a to b. Potential energy only. Much easier. You will want to have your formula for grav potential energy handy.

The formula is Grav potential energy= -GMm / r

I think the answer would be either A or B.

 

[Delphi51]

It seems clear to me you are misunderstanding something, but I'm not supposed to just tell you the answer. Can you explain your reasoning leading to A or B? They are rather different! A says path 1 has the highest change in PE while B says path 1 has the lowest change in PE. Both say 2, 4 and 6 have the same energy - why do you think that is true?