Few questions regarding space...

[Woolygimp]

There's a few things that I've seen on television that absolutely do not make sense so I just want to clarify.

When you see a spaceship fly by you always hear the engines pulsing. Well how can sound exist in space when it's a vacuum and there are no particles in which vibrations can exist?

How can fire exist in space without oxygen or being powered by excessive energy such as a byproduct of fusion?

For this one let's assume you have a 25hp space drive. Since everything in space is weightless, shouldn't this 25hp space drive be able to propel a basketball sized craft just as fast as something like the Death Star?

Also if a person were to have a stable platform for his leg muscles to operate, couldn't he move something as large as the Death Star if there were no counter forces operating against him?

Why do they constantly show things decelerating in space without the use of counter thrusters since inertia without resistance should result in perpetual motion?

[m_the0ry]

[ QUOTE ]
There's a few things that I've seen on television that absolutely do not make sense so I just want to clarify.

When you see a spaceship fly by you always hear the engines pulsing. Well how can sound exist in space when it's a vacuum and there are no particles in which vibrations can exist?

[/ QUOTE ]

It doesn't. TV is fake.

[ QUOTE ]
How can fire exist in space without oxygen or being powered by excessive energy such as a byproduct of fusion?

For this one let's assume you have a 25hp space drive. Since everything in space is weightless, shouldn't this 25hp space drive be able to propel a basketball sized craft just as fast as something like the Death Star?


[/ QUOTE ]

The answer lies in one of the basic laws of physics, conservation of momentum, which states that for any closed system (and a spaceship in the vacuum of outer space is pretty much as closed of a system as you can get) the product:

m*v

remains constant, where m = mass and v = velocity. How jet engines work is by expelling mass in the form of jet fuel as fast as possible in the opposite direction of intended travel. By giving the jet fuel momentum in the opposite direction of the target movement, the momentum of the entire system (fuel + spacecraft) must balance out to zero. This is accomplished by giving the spaceship momentum in the direction of travel. 'For every action there is an equal and opposite reaction'. For example, imagine you are sitting on a skateboard and have a medicine ball in your lap. If you throw the medicine ball away from you, you will roll away from the direction you threw the ball. The harder you throw the ball, the more you move. Same idea. As for fire in space, when oxygen is needed as a component for fuel combustion (combustion happens to be one of the best ways to make the fuel move really fast, and impart the most momentum on the ship) then it is mixed into the fuel. Much of the fuel tank you see is filled with liquid oxygen.


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Why do they constantly show things decelerating in space without the use of counter thrusters since inertia without resistance should result in perpetual motion?

[/ QUOTE ]

They should. TV is fake.

[Woolygimp]

[ QUOTE ]
[ QUOTE ]
There's a few things that I've seen on television that absolutely do not make sense so I just want to clarify.

When you see a spaceship fly by you always hear the engines pulsing. Well how can sound exist in space when it's a vacuum and there are no particles in which vibrations can exist?

[/ QUOTE ]

It doesn't. TV is fake.

[ QUOTE ]
How can fire exist in space without oxygen or being powered by excessive energy such as a byproduct of fusion?

For this one let's assume you have a 25hp space drive. Since everything in space is weightless, shouldn't this 25hp space drive be able to propel a basketball sized craft just as fast as something like the Death Star?


[/ QUOTE ]

The answer lies in one of the basic laws of physics, conservation of momentum, which states that for any closed system (and a spaceship in the vacuum of outer space is pretty much as closed of a system as you can get) the product:

m*v

remains constant, where m = mass and v = velocity. How jet engines work is by expelling mass in the form of jet fuel as fast as possible in the opposite direction of intended travel. By giving the jet fuel momentum in the opposite direction of the target movement, the momentum of the entire system (fuel + spacecraft) must balance out to zero. This is accomplished by giving the spaceship momentum in the direction of travel. 'For every action there is an equal and opposite reaction'. For example, imagine you are sitting on a skateboard and have a medicine ball in your lap. If you throw the medicine ball away from you, you will roll away from the direction you threw the ball. The harder you throw the ball, the more you move. Same idea. As for fire in space, when oxygen is needed as a component for fuel combustion (combustion happens to be one of the best ways to make the fuel move really fast, and impart the most momentum on the ship) then it is mixed into the fuel. Much of the fuel tank you see is filled with liquid oxygen.


[ QUOTE ]

Why do they constantly show things decelerating in space without the use of counter thrusters since inertia without resistance should result in perpetual motion?

[/ QUOTE ]

They should. TV is fake.

[/ QUOTE ]

You sort of missed a few points, when I was referring to fire in space I wasn't talking about the fire coming from a jet engine. I understand where the oxygen is coming from in that circumstance, I'm talking about in television shows when you see things explode and burn. I understand that if a space shuttle were to explode the oxygen would give rise to fire for a short period of time but it would not burn indefinitely.

Also, I'm not saying a 25hp engine would be as fast as a 25,000,000,000hp engine. I'm asking whether or not a 25hp would propel an object of any size/mass at the same velocity as any other object due to the inherent properties of a weightless environment?

[kerowo]

Yes a 25hp space engine could move a death star as easily as a bicycle in space, just not as quickly. Don't confuse mass with weight. The death star has a bucket load more mass than a bicycle and will take much longer to accelerate than the bicycle.

[m_the0ry]

Horsepower is a measurement of power so energy/second

.5m(v^2) = energy

so there's the relationship. mass doesn't decrease in space, only weight does. The smaller the mass the faster it will move and accelerate.

[SamIAm]

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The death star has a bucket load more mass than a bicycle

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The "bucket load" is the standard unit of mass for the empire. (The rebellion switched to Metric.)

[kerowo]

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[ QUOTE ]
The death star has a bucket load more mass than a bicycle

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The "bucket load" is the standard unit of mass for the empire. (The rebellion switched to Metric.)

[/ QUOTE ]

It replaced the old unit of 'VW Bug' due to ambiguity between classic bugs and new bugs.

[soon2bepro]

In an enterview, George Lucas said he knew of all these things when he made Star Wars, but he felt it would be boring to have these fights happen with real outer space physics.

By the way, you didn't mention it, but did you notice how most fictional starships need to turn around the way an airplane would? That doesn't make any sense either, but it's more fun I guess.

[kurto]

Babylon 5's spaceships always used thrusters for steering. Their portrayal of space ships (at least the human ones) was probably a little closer to reality then most.

[Capitan23]

1. no sound in space tv is fake.
2. fire doesn't really exist in space.
3. yes a basketball can move as fast as a death star
4. yes you can move a death star with your thrust, but say the death star is 5000 times bigger than you, it will move 5000 times slower than you will when you push away.