How does momentum affect the motion of objects in a friction-less environment?

[marosa4]

Totally irrelevant. I am not assigning any meaning here. You asked if a specific effect had ever been observed, and it has, conclusively. It is demonstrably possible for a reaction engine velocity to exceed the exhaust velocity.

Never been observed by anyone other than NASA then is the answer you have for me.
Never observed on earth, and cannot be for some unexplained reason.
They claim to be able to measure Gravitational Waves, and curved spacetime, from earth, but can't demonstrate a simple chemical rocket working like they claim. Why is this unbelievable?

 

[Dale]

Never observed on earth, and cannot be for some unexplained reason.

I explained it already: air resistance.

but can't demonstrate a simple chemical rocket working like they claim.

They have demonstrated it multiple times. The delta v to the space station is about 9 kps and the space shuttle’s exhaust velocity is only about 4 kps. Do you really want to claim that no space shuttle ever made it to the space station?

So it's impossible to prove this effect of what should be standard physics, unless I go into space. So if I think the space experiment is flawed, and want to check the concept, and reproduce the experiment, I can not do any test on Earth?

No, it is not impossible. It is just pointless and expensive, so it hasn’t been done to my knowledge. You can certainly do the test, all you have to do is pay for it. I doubt that you will be able to convince anyone else to chip in.

 

[Dale]

This is the first time you have mentioned an equal mass projectile.

Say you have a 1 kilogram cart with a 128 kilogram projectile, a 64 kilogram projectile, a 32 kilogram projectile, a 16 kilogram projectile, an 8 kilogram projectile, a 4 kilogram projectile, a 2 kilogram projectile and a 1 kilogram projectile stacked on top in an inverted pyramid.

You shoot off the 128 kilogram projectile and gain 50 kph.
You shoot off the 64 kilogram projectile and gain another 50 kph
You shoot off the 32 kilogram projectile and gain another 50 kph
You shoot off the 16 kilogram projectile and gain another 50 kph
You shoot off the 8 kilogram projectile and gain another 50 kph
You shoot off the 4 kilogram projectile and gain another 50 kph
You shoot off the 2 kilogram projectile and gain another 50 kph
You shoot off the final 1 kilogram projectile and gain a final 50 kph.

Total 400 kph. See the Tsiolkovsky rocket equation for the case where the fuel is used continuously rather than in discrete shots.

This would be relatively inexpensive, and if you kept the speeds low enough and the times short enough then air resistance could be minimal. You would only need three stages to prove the point. First stage gets it up to half the “exhaust” velocity, second stage gets it to “exhaust” velocity, and the third stage pushes it past “exhaust” velocity.

 

[weirdoguy]

Once upon a time, the "peers" said the Earth was flat.

I think that you really should read up on how modern empirical sciences work. Bringing up times where science (in a modern sense, with its modern rigour) barely existed shows only that you don't know much about the things you're trying to talk about... Thus your attitude is a little bit inappropriate.

 

[cjl]

No, The exhaust gas is ALWAYS much faster than the rocket or plane. I never said otherwise. What you are claiming is that somehow the plane or rocket can go faster than the exhaust gas from its own engine.

Actually, this is incorrect for every single orbital rocket. A solid fuel rocket motor has an exhaust velocity of around 2.5km/s, and liquid fuel ranges from 2.5-5 km/s. Orbital velocity is in excess of 7 km/s, so every rocket launched to orbit or escape ends up traveling faster (relative to its launch pad) than the exhaust velocity.

 

[berkeman]

Note that @marosa4 has left the building, so it's probably not necessary to try to convince him of his error any more. Several of his posts have been deleted.

 

[sophiecentaur]

Newtons law says and equal and opposite reaction, not any provision for multiplication of the velocity on one side.

Let me put this another way. If YOU were teaching a class of young people about this claimed effect, and you wanted to perform an experiment to show how a slow speed, re applied to an object can increase its speed to be greater than the input speed, how would you do it?

There is no way that you can honestly demonstrate any of the relationships that they learn. There are demonstrations that give a flavor of a theory but that’s pretty much all any of us can expect. Even a simple electrical circuit measurement needs the use of meters and power supplies that they cannot understand and they have to take things on trust.
You cannot reject an established theory on the basis that it is inconvenient to set up an experiment that will satisfy someone with little knowledge.
I imagine you were interested and impressed with the discovery of the Higgs Boson. You accepted that it was all beyond you (and most of the rest of us) and i’d bet you didn’t need the full explanation.
Newton 1, 2 and 3 are demonstrated to high accuracy all over the place when Engineers make mechanisms work. What more do you want?

 

[Dale]

There is no way that you can honestly demonstrate any of the relationships that they learn. There are demonstrations that give a flavor of a theory but that’s pretty much all any of us can expect.

I agree. I think that if I wanted to "demonstrate" this for a class (not sure why) then I would just go with the statement given by @cjl above. It is very straightforward and uses data that they can easily google to verify even if they cannot do the experiment themselves. I wouldn't spend more than 2 minutes on the topic.

 

[jonk75]

When a bullet accelerates out of a gun, the recoil of the gun is much slower than the speed of the bullet.

 

[A.T.]

When a bullet accelerates out of a gun, the recoil of the gun is much slower than the speed of the bullet.

Unless the bullet is heavier than the gun. Same with rockets, which consist mostly of propellant mass, and thus can get faster than its exit velocity,

 

[jonk75]

Unless the bullet is heavier than the gun. Same with rockets, which consist mostly of propellant mass, and thus can get faster than its exit velocity,

Yes, that’s what I meant. The bullet traveling faster than the recoil of the gun is an example of the kind of experiment the OP was asking for - i.e. the velocity of the bullet ends up faster than the velocity of the recoil. It’s easy enough to demonstrate on earth. Even a skinny bloke pushing off a fat bloke in a swimming pool demonstrates it. I don’t see why the OP was making such a fuss.

 

[Dale]

Even a skinny bloke pushing off a fat bloke in a swimming pool demonstrates it.

Nice! I wish I had thought of that example. I was so focused on rocket engines and why you don't do those in the atmosphere that I failed to generalize to an everyday example like that.

 

[russ_watters]

Nice! I wish I had thought of that example. I was so focused on rocket engines and why you don't do those in the atmosphere that I failed to generalize to an everyday example like that.

First day of freshman physics was an auditorium demonstration with several sections, demonstrating many concepts. It included a demonstration with the largest guy, smallest girl and two skateboards. "Push!"

I just went looking for spring-launched toys that could be adapted to demonstrate this issue, but found this instead:
https://mansionlabs.com/search-results.html
[search: momentum]