Gpe (1 Viewer)

[>monkey<]

hey guys i just have 2 questions im kinda stuck with n the text books didnt really help

1. Explain the reason for the selection of infinity as the place of zero gravitational potential energy

2. Explain how the selection of the zero level at the Earths surface, results in any point within a gravitational field having a negative gravitational potential energy

 

[FinalFantasy]

Gravitational potential energy is the energy of a mass due to its position within a gravitational field. Bcoz of da inverse square relationship in the Law of UNiversal Gravitation, the force of attraction between a planet and an object will become zero only at infinite distance away from the planet.

 

[FinalFantasy]

also E=-Gm1m2\r, da limit of r-->00 -Gm1m2\r=0, cuz lim x-->00 1\x=0
(correct me if im wrong)
Edited to make it look better

 

[FinalFantasy]

2. Explain how the selection of the zero level at the Earths surface, results in any point within a gravitational field having a negative gravitational potential energy

Since work is done on an object, when it is moved to infinity, all objects in da gravitational field have -VE gravitational potential energy..
hmm.. i guess that's not quite explaining..

 

[richz]

the negative is there because it indicates, that gravity is an attractive force and work must be done against it to pull the masses apart