Space travel questions (1 Viewer)

[duck]

Hi,
I have been assigned to investigate 3 conditions that would affect an astronaut during launch.

The question is a bit vauge, but i've chosen to explain:

1. change in acceleration and the effect on an astronaut (g force increase)
2. Earth's daily rotation and fuel saving methods (?)
3. Atmospheric drag

Do these sound right?

I also need to discuss why the forces acting on the astronaut will increase to 3W (3 * ma) during launch. Would this relate to the first point above? I've found http://www.phys.unsw.edu.au/~jw/FAQ.html#space but it doesn't really explain it.

Thanks for the help.

 

[Ragerunner]

Your first one is correct. I would say something like if the mass of the rocket decreases during flight and the thrust remains constant, the acceleration of the rocket (and astronauts) increases. Thus the force experienced by the astronaut increases.
You can also relate it to the Law of conservation of momentum.

Second one is hard to say that it really affects the astronauts.

Initially I would of thought of safety features. i.e. use a contoured couch and lie facing upwards to avoid eyes popping out. (Which is in relation to your first choice about g-forces).

I was also thinking about heat problems that you could elaborate on. Also the escape velocity required.

Would be best to give a list of things you want to do and check with your teacher as to whether it is appropriate or not.

 

[...]

3conditions..

err...the position they sit in is very important as to how the blood flows...

communication problem..but thats more like landing

 

[Ragerunner]

lol.

If they had communication problem at the start, they wouldn't launch it. WOULD THEY? stupid Americans

Yes, position they sit is important. To avoid blackouts/redouts.
But that is in relation to g-forces, so i'm not sure whether he can put that as a condition.

 

[duck]

Condition 1 Change in acceleration

In a rocket, fuel constitutes a large percentage of the mass. During launch, the fuel is spent thus reducing the total mass of the rocket. According to Newtons second law (f = ma), as the thrust/force is constant (the momentum of the gases escaping out of the rear of the rocket must equal the forward momentum of the rocket due to law of conservation of momentum) and the mass is reducing as the fuel is spent, the acceleration of the rocket (and astronaut) must increase.

This in turn increases the force experienced by the astronaut. The gravitational field of the earth also decreases as the rocket increases altitude. The atmosphere also becomes thinner as the rocket increases altitude, all resulting in increased acceleration.

Due to the rapid increase in acceleration, rockets are designed in multiple stages with the ability to control the flow of fuel to the engine to reduce acceleration when the g-force becomes unbearable.. Specifically designed contoured seats are made facing up to prevent blackout due to the excessive force.

 

[Ragerunner]

That would be a perfect answer in my opinion.

But if it's an assignment you still probably need to elaborate more.

 

[Dash]

1) The condition that you stated before (ie changing acceleration) is a very good one. Its called "momentum conservation" and explains the variations in g forces on an astronaut during launch. You could also relate this point to single stage and multi-stage rockets.

About the other 2 conditions, I would talk about what Ragerunner said:

2) The effects of g forces and how to overcome them.
- moulded seats
- eye balls in
- pressurised space suits etc...

3) The effects of heat on the astronaut and how to overcome it.
- ceramic tiles
- insulation

Remember to include a lot of detail when answering these questions.

 

[juggernaut]

Change your 2 and 3 to what Dash said ^^^^^
because they arent really direct affects on the astronaut

 

[Rahul]

Originally posted by Ragerunner
I would say something like if the mass of the rocket decreases during flight and the thrust remains constant, the acceleration of the rocket (and astronauts) increases. Thus the force experienced by the astronaut increases.

good point this one.
as the fuel is burnt off, the force from it that is propelling it will remain constant. but the mass that is being propelled will decrease, hence more acceleration, therefore, more g-forces on astronauts.