HSC Physics Marathon 2013-2015 Archive (1 Viewer)

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Menomaths

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re: HSC Physics Marathon Archive

These questions are the hardest type of mc questions
 

Fizzy_Cyst

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re: HSC Physics Marathon Archive

I will send a Freddy frog to the first person to get part 2 of my previous question correct *

* conditions apply
 

Menomaths

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re: HSC Physics Marathon Archive

I will send a Freddy frog to the first person to get part 2 of my previous question correct *

* conditions apply
1)1.03*10^-3N towards Jupiter's centre
2)2.3*10^11m?
 

psychotropic

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re: HSC Physics Marathon Archive

Mount Everest is the worlds tallest mountain, however, it is not the point on the Earths surface at which acceleration due to gravity is the lowest. Explain.
Gravitational field strength is given by the formula g = GM/r^2. Although we may expect it to have the lowest value of g, since g decreases with the radius (and hence altitude) we are above the earth's surface, there are many reasons why Mt Everest may not have the lowest gravitational field strength.
1. the earth under and on Mt Everest may be more dense than other parts of the earth, which would mean that there is a greater localised mass near Mt Everest. By the equation given above, that would increase the value of g at Mt Everest
2. Mt Everest is located between the equator and the poles. Because of the ellipsoid shape of the earth, the earth has a larger radius at the equator. This means that a mountain at the equator may have a lower value of g.
3. Further, the axial rotation of the earth creates a pseudo centrifugal force that acts outwards from the centre of the earth, reducing the value of g. Because the axial rotation is most prominent at the centre, so is this effect. Mt Everest is not very close to the equator, and hence its value of g is not greatly impacted by this effect. Rather, a mountain or high land feature at the equator would be.
Therefore, because of the above factors, Mt Everest understandably does not have the lowest acceleration due to g. Rather, it would be expected that a high land feature or mountain at the equator MAY have the lowest value of g.
 

superSAIyan2

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re: HSC Physics Marathon Archive

redid part 2, got 2.87 x 10^11 m (same as psychotropic). I realised i didnt expand the perfect square properly
 

omgiloverice

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re: HSC Physics Marathon Archive

2) 5.2x10^(11) m away from Jupiter ? o.o I doubt I'm right..
 
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Menomaths

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re: HSC Physics Marathon Archive

I see my mistake :(
 

Fizzy_Cyst

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re: HSC Physics Marathon Archive

Must. Come. Up. With. Something. Harder. For. BOS. Nerds.
 

Menomaths

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re: HSC Physics Marathon Archive

Can someone show working for the question Fizzy put up? I'm so incompetent in maths :(
 

hayabusaboston

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re: HSC Physics Marathon Archive

Is 2 infinite distance?
Am I interpreting the question right?
since one planet's mass is different to anothers, the question asks at what distance from one planet will the gravitational force of attraction to that planet be equal to the gravitational force of attraction to the other planet so giving no net force?
So its just modifying r in the formula right?
 

Menomaths

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Am I interpreting the question right?
since one planet's mass is different to anothers, the question asks at what distance from one planet will the gravitational force of attraction to that planet be equal to the gravitational force of attraction to the other planet so giving no net force?
So its just modifying r in the formula right?
Yeah, when both of their 'F' is equal on the probe, it'll experience 0 net force but I don't know how to work it out :angry:

ps i thought the answer was infinite because i never knew he meant the probe being in between the two planets
 

psychotropic

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re: HSC Physics Marathon Archive

look at the field lines from the north and south poles
 
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