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Physics, Astronomy & Cosmology / WHat is the the fuel consumption of the SSME?

« on: 29/04/2018 18:30:26 »

God I’ve done a lot of rocket stuff.
Anyway, I’ve been doing a bit of looking on the internet, and I think I understand that ISP = Thrust/fuel weight flow rate. I know that the SSMEs have a thrust of 480,000 lbf at SL. I can’t remember their ISP (a quick Wikipedia will do the trick I’m sure), but since I’m a little confused about the units, could someone please use this info to tell me how many kilos (or any other unit of mass) of propellant an SSME (at max thrust) burns per second? Cheers.

2

Physics, Astronomy & Cosmology / Do I weigh as much as the Earth?

« on: 09/03/2018 20:45:50 »

This is going to sound weird and stuff, but I’ll go for it.
Gravitational force is equal to: G((m1xm2)/rxr). Which means th force of gravity on me by the Earth is the same as the gravitational force on the Earth by me.
So do I weigh the same as the Earth? Or am I missing something?

3

General Science / Could other types of energy except heat change a state?

« on: 09/03/2018 20:38:04 »

Hello,
Just been thinking, and I was wondering about how a substance changes state. If heat is applied, the energy is used to break forces of attraction between the molecules, changing its state. I was thinking, however, could other types of energy be used to do this? Or just is it heat? Could, say, electrical or sound energy do the trick?
Thanks

4

Physics, Astronomy & Cosmology / Why are there metals inside the Sun?

« on: 22/09/2017 20:08:49 »

Hello, just doing some research and found that the Sun is around 1% metal. 0.1% of which is iron. Now I've studied nuclear fusion at an in depth level, and I'm pretty damn sur en that the Sun is still in its hydrogen core fusion stage. The only elements it should be synthesising, I though, was helium, from all the hydrogen it has. It only starts fusion of helium into carbon after becoming a red giant, and a thought, being a low mass star, that at no point in its life would it manufacture oxygen, silicon, neon magnesium or iron. Why is there metals in it? Is it residue from when the Solar system formed - i.e debris that accumulated, and that it did not form itself; OR have I missed something important, and the Sun is in fact manufactring heavy elements at this point?
Any help would be greatly appreciated!
Thanks.

5

Plant Sciences, Zoology & Evolution / What do bumble bees do with nectar when they come back?

« on: 27/08/2017 23:32:18 »

Honey bees are well studied. But Bumble bees are not.
Some sources say they make honey in small amounts.
Others say they feed their young nectar.
So, do workers make honey, and feed the young honey?
OR do they come back with nectar, feed the nectar to whatever young, then turn the surpluss into storage honey?
OR something else?
Sorry being pedantic!
Thanks

6

Physics, Astronomy & Cosmology / How much thrust does the space shuttle ssme produce in lbs at max? (SL)

« on: 01/08/2017 18:42:19 »

Before you answer:
Many different sources say different things. For example:
Different NASA journalist sources say either that each has 375000 lbs, or 418000lbs
Wikipedia says 418000 lbs, based on the Aerojet website, which says the same.
However, Dr. David Baker, a editor of spaceflight, who worked as an engineer on NASA apollo, Gemini and space shuttle programmes, says they each have 550000lbs of thrust. He also backs this up with a story of the history and development of how the SSME came to be like this (as part of a race between Aerojet and Pratt and Whitney).
Into black, a novel of a true story of he space shuttle, says the same, with the same story to back it up, and the author has researched many sources and interviewed NASA members.
Who should I believe?

7

The Environment / Would insect conservation be easy?

« on: 25/07/2017 22:42:48 »

He IUCN uses the species total number to see what it's rating would be.
But, surely it would be different for insects? If not, u could literally just breed two insects and boost the population to endangered from a critically endangered start. But then insects die out easily... essentially, what I'm asking is... does the number of insects or other numerous invertebrates have to be higher to qualify as the same IUCN rating as a given mammal. E.g, a mammal would be CR at... I dunno... 200 individuals (not accurate), but then an insect would be CR at 5000. Or do they just assume the same. If so, wouldn't insect conservation be dead easy?

8

Technology / why are solid propellant rocket fuels not used, if they are more powerful?

« on: 25/07/2017 22:37:22 »

I was looking a differences between the liquid and solid rocket fuels.
Apparently solid fuels are much denser and more powerful, but are simply less efficient.
What's wrong with that? Why don't we use them?

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Plant Sciences, Zoology & Evolution / How do edible frogs reproduce genetically?

« on: 25/07/2017 22:29:01 »

Basically, I know this may seem amteur, but how can edible frogs reproduce? Aren't they hybrids? I read that hybrids can't reproduce....any comments I would be very greatful :-)

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Cells, Microbes & Viruses / How do bacteria evolve?

« on: 30/06/2017 22:02:38 »

Sorry, this may seem amateur, but how do bacteria evolve? I thought they were all clones? Also, how does this work in animals, if all the DNA is passed on from parents? How do variations rise up?

11

Physics, Astronomy & Cosmology / Is acceleration due to gravity reliant only on distance and mass?

« on: 29/06/2017 21:08:55 »

I know that Fgrav - G ((m1m2)/r x r) and that f - ma (in this case m2 x a) If u want to work out acceleration due to gravity, u therefore do: Acceleration due to gravity - (G ((m1m2)/r x r))/m2. The m2 would then cancel out to: Agrav - G(m1/(r x r)). So acceleration of an object due to gravity is dependent on the distance between the centre of mass of the two objects, and the mass of the object that the given object is accelerating towards. Correct?

12

Physics, Astronomy & Cosmology / Are black holes really holes?

« on: 29/06/2017 21:01:46 »

Every website I've read describes black holes as an infinite curve in space time.
However, from what I know, I believe a singularity is just a tiny, dense ROUNDED, celestial object, whose GRAVITY can be represented as a well. Is this correct?
And is so, is the event horizon an imaginary sphere around the singularity?

13

Marine Science / How do siphonophores reproduce?

« on: 29/06/2017 20:24:52 »

Hi, I was reading about siphonohpores and have a great website describing all the different types of zooid, however, it doesn't describe HOW a siphonophores reproduces.
I researched a bit, and apparently, they can either broadcast sperm and egg into the water, or bud of eudoxids. Is this correct? If so, how do they then developed after fertilisation?