question i dont understand, can someone explain it (1 Viewer)

[fantasy8]

Outline the rationale behind choosing infinity as the point where objects in Space have zero Ep

dont understand

 

[fantasy8]

also Account for the gravitational potential energy of a mass in a gravitational field having a negative value

 

[rama_v]

Well think about it
At an infinite distance away, teh gravitational potential energy becomes zero, because the object is so far away that the gravitational force exerted on it by the planet is so small, that it is in fact zero at an infinite distance.

This also explains why GPE is a negative number, because the gravitational potential energy is rising every time your altitiude above a primary body increases. (more work is done to put you into that higher location). But if you keep on increasign in altitude/distance, you eventually get to a point where GPE is zero. This is only possible if GPE is negative...

 

[serge]

Well think about it
At an infinite distance away, teh gravitational potential energy becomes zero, because the object is so far away that the gravitational force exerted on it by the planet is so small, that it is in fact zero at an infinite distance.

This also explains why GPE is a negative number, because the gravitational potential energy is rising every time your altitiude above a primary body increases. (more work is done to put you into that higher location). But if you keeo on increasign in altitude/distance, you eventually get to a point where GPE is zero. This is only possible if GPE is negative...

I think i read somewhere that GPE is negative because
it will 'take away' energy from the system to move the objects closer...

it might be simplistic but would I get any marks if i wrote that?

 

[rama_v]

I think i read somewhere that GPE is negative because
it will 'take away' energy from the system to move the objects closer...

it might be simplistic but would I get any marks if i wrote that?

You may get some marks if you write that
The way I think about it is that you put energy into a body to give it GPE, and when it fall sback down, it loses GPE, hence doing work in the process.

 

[frenzal_dude]

this thing took me a while to comprehend 2, the way rama v explained it was good.

You have 0 GPE at infinity because you are outside the gravitational field.

As you fall to earth from that infinite point, you lose GPE since you are getting closer to earth, and therefore have less distance to fall, and therefore less GPE, then that means that your GPE gets less than 0 which is negative.

 

[darkwarrior2]

hey the closer you are to earth the higher the GPE or lower?

 

[rama_v]

hey the closer you are to earth the higher the GPE or lower?

As you fall to earth from that infinite point, you lose GPE since you are getting closer to earth, and therefore have less distance to fall, and therefore less GPE,

10characters

 

[biscuit]

Well if GPE at infinity is defined as zero, then the closer you get to earth, the LESS GPE it has (negative value) --> this is because it gains in kinetic energy, thus it looses potential energy