HSC Physics Marathon 2013-2015 Archive (1 Viewer)

Status
Not open for further replies.

premskies

Member
Joined
Sep 21, 2011
Messages
140
Gender
Undisclosed
HSC
2013
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

Member
Joined
Sep 21, 2011
Messages
140
Gender
Undisclosed
HSC
2013
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

Member
Joined
Dec 27, 2012
Messages
272
Gender
Undisclosed
HSC
2009
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

Active Member
Joined
Jul 8, 2011
Messages
1,509
Gender
Male
HSC
2013
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

Member
Joined
Sep 2, 2012
Messages
44
Gender
Male
HSC
2013
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 :)
 
Last edited:

bleakarcher

Active Member
Joined
Jul 8, 2011
Messages
1,509
Gender
Male
HSC
2013
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

Active Member
Joined
Jul 8, 2011
Messages
1,509
Gender
Male
HSC
2013
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

Member
Joined
May 11, 2012
Messages
160
Gender
Male
HSC
2013
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

Owner @ Sigma Science + Phys Goat
Joined
Jan 14, 2011
Messages
1,212
Location
Parramatta, NSW
Gender
Male
HSC
2001
Uni Grad
2005
Re: 2013 HSC physics marathon

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

iBibah

Well-Known Member
Joined
Jun 13, 2012
Messages
1,374
Gender
Male
HSC
2013
Re: 2013 HSC physics marathon

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

AnimeX

Member
Joined
Aug 11, 2012
Messages
588
Gender
Male
HSC
N/A
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

This too shall pass
Joined
Nov 6, 2011
Messages
3,730
Gender
Male
HSC
2013
Re: 2013 HSC physics marathon



 

Sy123

This too shall pass
Joined
Nov 6, 2011
Messages
3,730
Gender
Male
HSC
2013
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.

=======================



 
Last edited:

RealiseNothing

what is that?It is Cowpea
Joined
Jul 10, 2011
Messages
4,591
Location
Sydney
Gender
Male
HSC
2013
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.

=======================



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

iBibah

Well-Known Member
Joined
Jun 13, 2012
Messages
1,374
Gender
Male
HSC
2013
Re: 2013 HSC physics marathon

Q: Calculate the effective value of 'g' at the equator. (Given g=9.81ms^-2)
 
Status
Not open for further replies.

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top