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

[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
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