Interesting shed projects

[Tim754]

'the rate at which you bugger off backwards'  about sums up this lot

[78rm80c]

We got 2 Rolls Royce Orpheus jets, one we. Keep at my work and im sitting next to the other right now lol

[pancho]

 Hey GMC, I suspect that gunpowder, like nitro methane. contains its own oxygen?

 Hey montynut, my eyes went crossed when I saw all those mathematical hieroglyphics (long time since I was belted for not reciting my multiplication tables) but I get whats happening.(I think!)

[Montynut]

Laws of physics for each force there is an equal although opposite reactive force.

Almost true. The law actually states: "for each reaction there is an equal although opposite reaction.

An example if you were in outer space and fired a gun (ignoring the fact that as there is no air would the bullet actually fire) the projectile would travel at a set speed in one direction and you would travel at the same speed in the opposite direction.

Not true. P=mv. Momentum is conserved so m1v1 = m2v2. The bullet buggers off at say 200m/s (v1) and it weighs say 0.05 kg (50 grams, m1) so P = 200 x 0.05 = 10. But you weigh 80kgs (m2) so 10 = 80 x v2 giving 0.8 m/s for v2 or the rate at which you bugger off backwards. See: http://en.wikipedia.org/wiki/Conservation_of_momentum#Conservation_of_linear_momentum

Your correct with your formula but the bullet weight and your weight are dependent on gravity therefore in space where gravity is minimal or effectively zero I believe that the resulting speed of the projectile and the person would be much closer to equal. Well that is my understanding. But does the relative masses of the two bodies compensate for this    my head hurts 

[Montynut]

ignoring the fact that as there is no air would the bullet actually fire

Hmmm, so if gunpowder needs oxygen to explode how does the oxygen get inside the little brass chamber when it’s already full of gunpowder??
And the brass chamber is usually hidden away inside metal components making it hard for oxygen to get in quickly.

And if we sit things on our lap when we are sitting down where does our lap go when we stand up??






If only the forum intellect could be harnessed for good instead of…  I've read that somewhere before 

I hate guns and was posing another question as I didn't really want to think about it I believe there is an oxidising component in the gunpowder.

[Montynut]

Hey GMC, I suspect that gunpowder, like nitro methane. contains its own oxygen?

 Hey montynut, my eyes went crossed when I saw all those mathematical hieroglyphics (long time since I was belted for not reciting my multiplication tables) but I get whats happening.(I think!)

I didn't post the formulas

[David Lahey]

Laws of physics for each force there is an equal although opposite reactive force.

Almost true. The law actually states: "for each reaction there is an equal although opposite reaction.

An example if you were in outer space and fired a gun (ignoring the fact that as there is no air would the bullet actually fire) the projectile would travel at a set speed in one direction and you would travel at the same speed in the opposite direction.

Not true. P=mv. Momentum is conserved so m1v1 = m2v2. The bullet buggers off at say 200m/s (v1) and it weighs say 0.05 kg (50 grams, m1) so P = 200 x 0.05 = 10. But you weigh 80kgs (m2) so 10 = 80 x v2 giving 0.8 m/s for v2 or the rate at which you bugger off backwards. See: http://en.wikipedia.org/wiki/Conservation_of_momentum#Conservation_of_linear_momentum

Your correct with your formula but the bullet weight and your weight are dependent on gravity therefore in space where gravity is minimal or effectively zero I believe that the resulting speed of the projectile and the person would be much closer to equal. Well that is my understanding. But does the relative masses of the two bodies compensate for this    my head hurts 

Tim's "conservation of momentum" equations do apply perfectly in space. The only confusing aspect is that he referred to the "masses" of the objects as their "weights".

[Montynut]

You correct Feetup I was just considering again and the relative mass still applies so Tim is correct. Now the important question how far would the projectile and person travel once the gun was fired Oh FFS forget it   

[David Lahey]

Their speed and direction would vary over time depending on the force of gravity generated by other masses that acted on them as they travelled.
It is only the initial velocities of the person and the bullet that can be calculated by the law of conservation of momentum
Saltpetre (potassium nitrate) is the oxidising agent in gunpowder. Bullets can be successfully fired in space and under water (provided the round is waterproof).

[David Lahey]

You correct Feetup I was just considering again and the relative mass still applies so Tim is correct. Now the important question how far would the projectile and person travel once the gun was fired Oh FFS forget it   

I was just starting to get interested too

[Tim754]

Tim's "conservation of momentum" ....... hey who is calling me a lazy bugger Wait sorry is some other Tim Tim754        well actually I am......

[TooFastTim]

Hey montynut, my eyes went crossed when I saw all those mathematical hieroglyphics (long time since I was belted for not reciting my multiplication tables) but I get whats happening.(I think!)

He he. To be honest so do mine (although I'm quite happy with Hills equation). I just cut and pasted Bernoullis equation and the Navier-Stokes equation. Both describe the behaviour of fluids.

Tim's "conservation of momentum" equations do apply perfectly in space. The only confusing aspect is that he referred to the "masses" of the objects as their "weights".

When I wrote that I knew somebody was going to pick me out for using the word weight. Dave you are correct I should have used mass.

Now the important question how far would the projectile and person travel once the gun was fired

In deep space? Assuming a (near) perfect vacuum and no nearby "massive" bodies? A bloody long way. Perhaps forever. At least until it falls under the influence of a massive body or the vacuum ceases to be near perfect. Hwever far that may be.

During the Gemini project when NASA was experimenting with space walks the problem soon showed itself. The simplest movement in space has consequences that you'd normally never dream of. For example: you lift your arm to reach for something, your arm rotates in its socket, there is an equal and opposite reaction so your entire body begins to rotate in the opposite direction. The astronauts would end up disorientated and exhausted.The problem was so bad that it nearly canned the moon race. But one astronaut thought about it and introduced special foot and handholds on the space craft and introduced training in the world biggest swimming pool. That astronauts name? Buzz Aldrin. Buzz is a clever phucker with a PhD in orbital mechanics. Buzz saved the moon race.

[GMC]

(although I'm quite happy with Hills equation).

Ah yes, Hills equation.
Finally you’re talking about something I know about.
Hills equation states that while rotational direction is a variable relative to rise and fall, the force required during rise and fall is directly proportional to the amount of wet washing on the hoist at the time.

During the Gemini project when NASA was experimenting with space walks the problem soon showed itself. The simplest movement in space has consequences that you'd normally never dream of. For example: you lift your arm to reach for something, your arm rotates in its socket, there is an equal and opposite reaction so your entire body begins to rotate in the opposite direction. The astronauts would end up disorientated and exhausted.The problem was so bad that it nearly canned the moon race. But one astronaut thought about it and introduced special foot and handholds on the space craft and introduced training in the world biggest swimming pool. That astronauts name? Buzz Aldrin. Buzz is a clever phucker with a PhD in orbital mechanics. Buzz saved the moon race.

Was that Buzz on the Halloween episode of Big Bang Theory the other night?

[TooFastTim]

Hills equation:



Used in designing particle accelerators. It implies that in addition to moving forward the particle oscillates on the x, y and z axes. Its kinda important if you want an accelerator to work.

Yes, apparently (I don't watch sitcoms) Aldrin was on the Big Bang Theory.

OK, I'll go back to having a sense of humour now 

[TooFastTim]

How many of us know why a jet engine moves through the air?
cheers

Seeing that you were being serious I'll answer your question as best I can.

If you think about a 2 stroke engine it has 2 strokes of the piston for a cycle. Basically these are compression and exhaust (I'll ignore how the mixture gets into the barrel for this explanation). A jet engine is similar. The air is sucked in at the front and compressed, the fuel is then burned and it is exhausted out the back:

A big difference is that the fuel is burned continuously and not in cycles.

After the fuel is burned at expands rapidly causing the turbine at the back to rotate which drives the compressor...



When Whittle first conceived the jet engine he realized that, with a turbo charged piston engine, you didn't really need the piston engine and that it could be replaced with just a combustion chamber and, if you look at his design (called a centrifugal jet) you'll see that's exactly what it is:



Look familiar?