# GPE question (1 Viewer)

#### jackleung34

##### Member
Your understanding is correct, and i suppose the explanation makes sense. However, the question doesn't prompt you to consider it from the earths F.O.R. so this shit is fucked. Where'd you get this Q

#### I97

##### Active Member
Half yearly. That's the thing i'm not quite sure why you need to take the earth as the F.O.R as it is not explicitly suggested in the question and is phrased pretty much like most other GPE questions where the graph for D would be used.

• Speed6

#### p0llex

##### Member
I don't see how B can be the answer:

Firstly GPE is always negative and approaches 0 as the distance approaches infinity, as shown in D.
Secondly the change in GPE should be greatest when the asteroid is close to the earth. B shows the asteroid having almost no change near earth and quickly approaching infinite GPE when it's far away, which makes no sense.

Have a talk to your teacher about it because it could just be a simple mistake on their part. For some example GPE graphs from the actual HSC which show the same shape as D have a look at:
27c of the 2014 paper
4 of the 2012 paper

#### photastic

##### Well-Known Member
Should be D. We know that GPE = - GMm/r , the greater the distance the higher the GPE as it will approach zero since we take infinite the point where GPE will equal to zero.

#### dmcstravick

##### New Member
It's b, at the furthest distance (infinite) the GPE is 0, as the distance gets greater the potential energy increases till an infinite distance.

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#### InteGrand

##### Well-Known Member
It's b, at the furthest distance (infinite) the GPE is 0, as the distance gets greater the potential energy increases till an infinite distance.

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Gravitational potential energy should always be negative assuming we use an infinite distance as the reference 0 point. So it can't be B, if we assume that.