1. ## Re: Geostationary Orbits (Q17)

Originally Posted by sja
it was specific to the stage where they were orbiting around the earth. the only two forces you had to bullshit about were earth's gravity and centripetal force - stating that velocity is perpendicular to the gravity as it goes around

they didn't ask for the re-entry because it's already been asked in previous years and wanted to expand the questions
Exactly, whoever it was going on about all that crap that DIDN'T have to do with the Q was just going over board. Though its nice to show knowledge, markers don't wanna read pages that don't relate to the question.

2. ## Re: Geostationary Orbits (Q17)

didnt the question say that the mission involved the craft being in geostationary orbit, and the specifically stated that it was guided back down the Earth? so yes, i think you would have to talk about other forces such as G-forces involved, not just the centripetal force=gravitational attraction relation

3. ## Re: Geostationary Orbits (Q17)

Originally Posted by angmor
didnt the question say that the mission involved the craft being in geostationary orbit, and the specifically stated that it was guided back down the Earth? so yes, i think you would have to talk about other forces such as G-forces involved, not just the centripetal force=gravitational attraction relation
i'm jsut thinking
isn't g-forces the forces tht humans feel?

the question asked and i quote it directly:
Analyse the forces acting on this SPACECRAFT during these parts of the mission
hence, no g-forces are felt by the spacecraft? im probably wrong here thoug h. lol

4. ## Re: Geostationary Orbits (Q17)

G-forces are a measure of acceleration. all matter can be accelerated (f=ma)

5. ## Re: Geostationary Orbits (Q17)

what the above guys' said...g-forces dont have to be felt by astronauts '

6. ## Re: Geostationary Orbits (Q17)

Originally Posted by myeewyee
G-forces are a measure of acceleration. all matter can be accelerated (f=ma)
g-force is used to express the apparent weight of an object in a multiple of the true weight......obviously there is no g-force for the spacecraft....since the acceleration equals to the gravitational acceleration.....
tht is g+a/g=g-g/g=0

7. ## Re: Geostationary Orbits (Q17)

no actually im pretty sure g-forces are also experienced when reentering the Earth's atmosphere...dunno its in the textbook. they have to minimise the g-forces on astronauts as they reenter earth

8. ## Re: Geostationary Orbits (Q17)

This question was fkn gay... I put down..

centripetal force due (Earth's gravitational attraction)
drag force causing spacecraft to lose altitude
g-forces on astronauts in re-entry

9. ## Re: Geostationary Orbits (Q17)

bs for the win.... i think all the forces are, gravity in orbit (slip in the "zero g" feeling) as well centripetal. thrust from rockets to get it into reentry position, air - friction force as it reenters (on top of gravity) g forces experienced is quite large... and i htink i slipped in parachutes creating drag which retards the spacecraft creating a further retarding force.

10. ## Re: Geostationary Orbits (Q17)

doesnt it only want forces on the craft, not on occupants?

11. ## Re: Geostationary Orbits (Q17)

Originally Posted by RingerINC

And during reentry the whole g-forces speel on people getting knocked the fuck out, also gravity.
ahahaha oh I love the way you worded that, I hope you wrote that in the exam! in terms of the physics yes i pretty much agree with you but ahaha you are funny

12. ## Re: Geostationary Orbits (Q17)

This question is Ghey.
You don't know that they are asking.

well...
Firstly, when orbitting, Centripetal force and Gravitational force are in equilibrium...
so that a velocity is needed to be maintained to keep the orbit

secondly, while re-entering...the optimum angle (5.2-7.2 degrees), Gravity. and weight force (F=mg).

That's what i have written.
=D

13. ## Re: Geostationary Orbits (Q17)

Originally Posted by aaaazzzz
g-force is used to express the apparent weight of an object in a multiple of the true weight......obviously there is no g-force for the spacecraft....since the acceleration equals to the gravitational acceleration.....
tht is g+a/g=g-g/g=0
Its irrelevant what its used for. What it IS is a measure of acceleration. Quote from wikipedia (yeah not the best source but i'm lazy):

The g is used primarily in aerospace fields, where it is a convenient magnitude when discussing the loads on aircraft and spacecraft (and their pilots or passengers). For instance, most civilian aircraft are capable of being stressed to 4.33 g (42.5 m·s−2, 139 ft/s²), which is considered a safe value. The g is also used in automotive engineering, mainly in relation to cornering forces and collision analysis.
kthx

Originally Posted by Wackedupwacko
bs for the win.... i think all the forces are, gravity in orbit (slip in the "zero g" feeling) as well centripetal. thrust from rockets to get it into reentry position, air - friction force as it reenters (on top of gravity) g forces experienced is quite large... and i htink i slipped in parachutes creating drag which retards the spacecraft creating a further retarding force.
Exactly what I said. I dunno if they'll pay marks for the parachute thing though

14. ## Re: Geostationary Orbits (Q17)

this question was easy

you didnt have 2 say anything about re-entry as it only asked for WHILE in orbit.

therefore
define geostationary orbit
you could say that the only force acting on the space shuttle is a centripetal force keeping it in orbit.

GRAVITY acts as this centripetal force.

you would then draw a diagram

then you would say something about WEIGHT.
define weight and how even though the astronauts feel weightlessness .. the weight force still exists an cannot be eliminated as they are still within the gravitational field of the planet and therefore experience 'apparent weightlessness'

yep yep.

15. ## Re: Geostationary Orbits (Q17)

Originally Posted by meekzy89
this question was easy

you didnt have 2 say anything about re-entry as it only asked for WHILE in orbit.
Yes, not reading the question normally does make them easier

Question quoted again
Parts of a space mission involve a spacecraft spending time in geostationary orbit and then returning safely to earth

Analyse the forces acting on this spacecraft during these parts of the mission

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