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HSC Physics Marathon 2013-2015 Archive (2 Viewers)

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premskies

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Re: 2013 HSC physics marathon

The slingshot effect is used by many spacecraft which travel within and beyond the solar system.
A spacecraft passes close to a a planet such that its gravity pulls the spacecraft into an arc or circular motion.It leaves with the same speed relative to the planet, but its speed is increased when viewed from an alternate frame of reference such as the Sun.
The acquired speed is large enough so that the spacecraft can travel away from the planet.
Good stuff, maybe instead of the first sentence though, I would have defined the slingshot effect.
 

premskies

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Re: 2013 HSC physics marathon

improved version^^
It's probably better defined as being the increase in velocity given to a spacecraft because it enters the gravitational field of a planet as it passes by.
 

Immortalp00n

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Re: 2013 HSC physics marathon

okay haha that's sorted, thanks prem!
new question:
At present, space travel is very expensive. NASA estimates that:
· the cost of sending 1 kg of cargo into Earth orbit is about $30 thousand
· the cost of sending one astronaut on a Space Shuttle mission for 2 weeks is about $200
million
· the cost of an unmanned probe to the surface of Mars is about $300 million
Use this information to account for the high cost of space travel and identify some measures that can be taken to improve flight efficiency.
 

bleakarcher

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Re: 2013 HSC physics marathon

Time to revive this bitch.

Explain why the speed of light is the limiting speed of any object in the universe.
 

kunal96

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Re: 2013 HSC physics marathon

If an object travelled at relavistic speeds it would experience mass dilation and its mass would increase. As a result of its mass increasing, its acceleration would decrease, assuming net force is constant. If this trend continues, the final outcome would be that as the object approaches the speed of light, its mass would approach infinity whilst its acceleration would approach zero, meaning that the object would not be able to further accelerate and hence the object would never be able to actually obtain the speed of light and thus it is referred to as being the limiting speed of an object in the universe.

Not too sure on the answer, havent actually covered space at school :)
 
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bleakarcher

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Re: 2013 HSC physics marathon

If an object travelled at relavistic speeds it would experience mass dilation and its mass would increase. As a result of its mass increasing, its acceleration would decrease, assuming net force is constant. If this trend continues, the final outcome would be that as the object approaches the speed of light, its mass would approach infinity whilst its acceleration would approach zero, meaning that the object would not be able to further accelerate and hence the object would never be able to actually obtain the speed of light and thus it is referred to as being the limiting speed of an object in the universe.

Not too sure on the answer, havent actually covered space at school :)
Yep, the general idea is right. I recommend using equations in your future responses.
 

bleakarcher

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Re: 2013 HSC physics marathon

haha thank you for the advice :) so which equations other than f=ma?
Yeah, I just meant applying the mass dilation formula to F=ma:
a=F/(m/sqrt(1-v^2/c^2))=F*sqrt(1-v^2/c^2)/m
As v->c, a->0.
 

omgiloverice

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Re: 2013 HSC physics marathon

If our galaxy, the Milky Way, is 20 kiloparsecs or 65 000 light-years in radius, calculate how fast a spacecraft would need to travel so that its occupants could travel right across it in 45 years.
Interesting question.
 

Fizzy_Cyst

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Re: 2013 HSC physics marathon

Fuuuuuar! Just noticed some of my tutor students pwning this thread. Well done you three :)
 

iBibah

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Re: 2013 HSC physics marathon

QUESTION: Explain why all low earth orbit satellites will eventually fall to the Earth’s surface.
 

AnimeX

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Re: 2013 HSC physics marathon

QUESTION: Explain why all low earth orbit satellites will eventually fall to the Earth’s surface.
All Low Earth Orbit (LEO) satellites will eventually fall to the Earth's surface due to atmospheric drag. Because LEOs are typically 160-2000km above the surface of the Earth, the satellite tends to collide with air molecules, this creates friction and thus kinetic energy is converted into heat and sound energy, thereby further losing kinetic energy and in time, altitude.
 

Sy123

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Re: 2013 HSC physics marathon



 

Sy123

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Re: 2013 HSC physics marathon

Just a note, am I allowed to ask questions which need students to solve simultaneous equations? Surely general maths students can do that.

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RealiseNothing

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Re: 2013 HSC physics marathon

Just a note, am I allowed to ask questions which need students to solve simultaneous equations? Surely general maths students can do that.

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You may want to fix up the given equation, you've done a typo I think.
 

iBibah

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Re: 2013 HSC physics marathon

Q: Calculate the effective value of 'g' at the equator. (Given g=9.81ms^-2)
 
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