On 12/05/2023 21:08, Java Jive wrote:
> Complaint lodged as follows ...
>
> BBC Inside Science Degenerating Into A Talk-Show
>
> The last two episodes of BBC Inside Science in particular, and other
> recent episodes more generally, have been talk-shows with little or no
> real scientific content.  While there may be a place for such
> talk-shows, that place is not in a science reporting programme such as
> 'BBC Inside Science'.  Please stick to the factual reporting of science,
> or at least remove the increasingly misleading word 'Science' from the
> programme title.

I've also thought about it, and moaned, but seems they can't.

There has to be a "way in" for folks to gain at least some interest, so
programmes are created to satisfy that 'd' word - diversity. Hence the
absymal "Repair Shop" and the necessary dumbing down of much else to
reality TV and tabloid newspaper standards.
>
> Discuss ... or not, as the mood takes you.

However, Science is reported daily all over the net at all sorts of
depth. Finding it just takes a search in google or YouTube. Then you
find something worth subscribing to.

I could bore you all and post up my interesting technical YouTube subs
list. I hardly watch broadcast TV.

We in the UK are failing to interest people in engineering and
technician jobs, they are seen as too boring complicated "rocket
science" and folks would rather stack shelves, aspire to be Football
players, and join the Gig economy.

The Science Museum has a very good exhibition in London (I've been),
that aims to reverse that and fill vacant jobs. The challenge is to get
parents to get their children through the front door.

https://www.sciencemuseum.org.uk/see-and-do/technicians-david-sainsbury-gallery

--
Adrian C

Also I have had two responses, both auto responders, but I only sent it
once, so why reply twice?
The best show was that short series where they took tech apart. The one on
the Amazon echo being particularly good I thought.
Brian

--

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"Adrian Caspersz" <email@here.invalid> wrote in message
news:kc9o59F70gvU2@mid.individual.net...
> On 12/05/2023 21:08, Java Jive wrote:
>> Complaint lodged as follows ...
>>
>> BBC Inside Science Degenerating Into A Talk-Show
>>
>> The last two episodes of BBC Inside Science in particular, and other
>> recent episodes more generally, have been talk-shows with little or no
>> real scientific content. While there may be a place for such talk-shows,
>> that place is not in a science reporting programme such as 'BBC Inside
>> Science'. Please stick to the factual reporting of science, or at least
>> remove the increasingly misleading word 'Science' from the programme
>> title.
>
> I've also thought about it, and moaned, but seems they can't.
>
> There has to be a "way in" for folks to gain at least some interest, so
> programmes are created to satisfy that 'd' word - diversity. Hence the
> absymal "Repair Shop" and the necessary dumbing down of much else to
> reality TV and tabloid newspaper standards.
>>
>> Discuss ... or not, as the mood takes you.
>
> However, Science is reported daily all over the net at all sorts of depth.
> Finding it just takes a search in google or YouTube. Then you find
> something worth subscribing to.
>
> I could bore you all and post up my interesting technical YouTube subs
> list. I hardly watch broadcast TV.
>
>
> We in the UK are failing to interest people in engineering and technician
> jobs, they are seen as too boring complicated "rocket science" and folks
> would rather stack shelves, aspire to be Football players, and join the
> Gig economy.
>
> The Science Museum has a very good exhibition in London (I've been), that
> aims to reverse that and fill vacant jobs. The challenge is to get parents
> to get their children through the front door.
>
> https://www.sciencemuseum.org.uk/see-and-do/technicians-david-sainsbury-gallery
>
>
> --
> Adrian C
>

Adrian Caspersz wrote:

>However, Science is reported daily all over the net at all sorts of
>depth. Finding it just takes a search in google or YouTube. Then you
>find something worth subscribing to.
>
>I could bore you all and post up my interesting technical YouTube subs
>list. I hardly watch broadcast TV.

It would be worth seeing.

Chris
--
Chris J Dixon Nottingham UK
chris@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.

The point here though is that one should expect a programme called inside
Science to be about science, not yet another discussion on climate change.
Brian

--

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"Chris J Dixon" <chris@cdixon.me.uk> wrote in message
news:1hu16i1ssmvh2jpkmgmt2b0beqtvpff7ua@4ax.com...
> Adrian Caspersz wrote:
>
>>However, Science is reported daily all over the net at all sorts of
>>depth. Finding it just takes a search in google or YouTube. Then you
>>find something worth subscribing to.
>>
>>I could bore you all and post up my interesting technical YouTube subs
>>list. I hardly watch broadcast TV.
>
> It would be worth seeing.
>
> Chris
> --
> Chris J Dixon Nottingham UK
> chris@cdixon.me.uk @ChrisJDixon1
>
> Plant amazing Acers.

On 15/05/2023 10:27, Brian Gaff wrote:
> The point here though is that one should expect a programme called inside
> Science to be about science, not yet another discussion on climate change.

Unfortunately the people who decide the budgets want wall to wall claims
about 'climate change'.

On 15/05/2023 19:14, MB wrote:
>
> On 15/05/2023 10:27, Brian Gaff wrote:
>>
>> The point here though is that one should expect a programme called inside
>> Science to be about science, not yet another discussion on climate
>> change.
>
> Unfortunately the people who decide the budgets want wall to wall claims
> about 'climate change'.

Brian is mistaken, neither of the talk shows specifically complained
about as being unscientific were actually about Climate Change, but were
on topics where it was relevant, so it got a mention in both. In the
first, a panel of 'experts' were asked to imagine that we were in the
year 2030, I think it was, and what Britain would be like given HMG's
policies - a totally vacuous and pointless programme more about
politics than science. In the second, another panel of experts was
asked if we could prevent natural disasters - again a thoroughly
pointless programme, because the obvious answer is "No! That's what
makes them 'natural'!", although it was correctly pointed out that we
could plan for them and so ameliorate the worst effects of them when
unfortunately they do occur.

However, as Brian correctly pointed out, Climate Change or no, they were
thoroughly unsuitable content for a science reporting programme.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 16/05/2023 13:58, Java Jive wrote:
>
> On 16/05/2023 10:46, Jeff Layman wrote:
>>
>> but as for preventing natural disasters, we can already divert
>> asteroids from hitting the earth. This has been known for some time
>> and was discussed on yesterday's "The Sky at Night".
>
> Weeeell, 'we can already' is putting it a bit strong  -  I watched the
> Sky At Night last night, and while the principle has been proven in
> practice, that's still a long way from having a system up and running
> that can do it with a useful probability of success.

The toilet is a wonderful spacetime for stopping to think about the world!

Although only barely consciously at the time I watched the Sky At Night
late last night, I was worried by the phrase "momentum enhancement" used
in the programme, and my unease came sharply into conscious focus today
when I was sitting on the throne. "That's not right!", I thought, "You
can't *create* momentum in a collision like that! Something else is
going on!". So I've just watched the clip again, and consequently do
think it's a very misleading way of describing what is really going on,
which is ...

When the ball is dropped onto the wet sand, nearly all of its momentum
is dissipated in the sand, mostly as heat, some as sound, so little of
it is conserved to be imparted to the container. However, when the ball
is dropped onto the pseudo-regolith, the greater springiness of the
material means that the collision is more elastic, and thus more of the
initial momentum of the ball is conserved and transferred to the
container. Therefore, strictly speaking, momentum has not actually been
'enhanced', just less of it lost!

Prog: https://www.bbc.co.uk/programmes/m001m027
Clip: https://www.bbc.co.uk/programmes/p0fmsqcy

Discuss in not more than 200 words. You should allow about 10 minutes
for this question.

Go to Exam Question 94 [for the PE readership].

--

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I may be contacted via the contact address given on my website:
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On 16/05/2023 19:46, Java Jive wrote:
>
> The toilet is a wonderful spacetime for stopping to think about the world!
>
> Although only barely consciously at the time I watched the Sky At Night
> late last night, I was worried by the phrase "momentum enhancement" used
> in the programme, and my unease came sharply into conscious focus today
> when I was sitting on the throne.  "That's not right!", I thought, "You
> can't *create* momentum in a collision like that!  Something else is
> going on!".  So I've just watched the clip again, and consequently do
> think it's a very misleading way of describing what is really going on,
> which is ...
>
> When the ball is dropped onto the wet sand, nearly all of its momentum
> is dissipated in the sand, mostly as heat, some as sound, so little of
> it is conserved to be imparted to the container.  However, when the ball
> is dropped onto the pseudo-regolith, the greater springiness of the
> material means that the collision is more elastic, and thus more of the
> initial momentum of the ball is conserved and transferred to the
> container.  Therefore, strictly speaking, momentum has not actually been
> 'enhanced', just less of it lost!
>
> Prog: https://www.bbc.co.uk/programmes/m001m027
> Clip: https://www.bbc.co.uk/programmes/p0fmsqcy
>
> Discuss in not more than 200 words.  You should allow about 10 minutes
> for this question.
>
> Go to Exam Question 94 [for the PE readership].

When the ball hit the wet sand it transferred all its momentum to the
bucket, and the bucket moved a bit.

When it hit the gravel all the ball's momentum was transferred, but _in_
_addition_ some of the gravel "splashed" upwards out of the bucket.
There was therefore additional momentum transferred from the bucket to
the gravel that went upwards.

It's a little hard to see of course, because gravity stopped it going up
far, but it's there.

Andy

On 16/05/2023 21:28, Vir Campestris wrote:
> On 16/05/2023 19:46, Java Jive wrote:
>>
>> The toilet is a wonderful spacetime for stopping to think about the
>> world!
>>
>> Although only barely consciously at the time I watched the Sky At
>> Night late last night, I was worried by the phrase "momentum
>> enhancement" used in the programme, and my unease came sharply into
>> conscious focus today when I was sitting on the throne.  "That's not
>> right!", I thought, "You can't *create* momentum in a collision like
>> that!  Something else is going on!".  So I've just watched the clip
>> again, and consequently do think it's a very misleading way of
>> describing what is really going on, which is ...
>>
>> When the ball is dropped onto the wet sand, nearly all of its momentum
>> is dissipated in the sand, mostly as heat, some as sound, so little of
>> it is conserved to be imparted to the container.  However, when the
>> ball is dropped onto the pseudo-regolith, the greater springiness of
>> the material means that the collision is more elastic, and thus more
>> of the initial momentum of the ball is conserved and transferred to
>> the container.  Therefore, strictly speaking, momentum has not
>> actually been 'enhanced', just less of it lost!
>>
>> Prog: https://www.bbc.co.uk/programmes/m001m027
>> Clip: https://www.bbc.co.uk/programmes/p0fmsqcy
>>
>> Discuss in not more than 200 words.  You should allow about 10 minutes
>> for this question.
>>
>> Go to Exam Question 94 [for the PE readership].
>
> When the ball hit the wet sand it transferred all its momentum to the
> bucket, and the bucket moved a bit.
>
> When it hit the gravel all the ball's momentum was transferred, but _in_
> _addition_ some of the gravel "splashed" upwards out of the bucket.
> There was therefore additional momentum transferred from the bucket to
> the gravel that went upwards.
>
> It's a little hard to see of course, because gravity stopped it going up
> far, but it's there.

No, that's the description that they gave, but it's incorrect - I said
'misleading' before, but, having thought about it some more, now I'm
saying that actually it's incorrect. You should be able to convince
yourself of this by conducting a simple thought experiment: suppose the
ball was dropped instead onto a hard elastic target such as a lump of
metal, all its momentum would then be converted into displacement of the
container holding the target and thus the displacement of the latter
would be much greater than for either of the demos in the SaN clip.

The error is that the law of conservation of momentum only applies with
'perfectly' elastic collisions, which we don't have here, on the
contrary, neither medium is either 'perfectly' elastic or 'perfectly'
inelastic, and moreover there is a significant difference in elasticity
between them, and this is what really explains the differing results.

Because conservation of momentum does not apply, to understand what's
really going on, you have to understand what's happening to the kinetic
energy of the impact. In both cases, while some of it is transmitted
through the medium into downwards momentum of its container, a
significant proportion of it is also lost as heat, sound, and distortion
of the medium surface, but the crucial point is that, because the two
mediums have different elasticities, different amounts of it is being so
transmitted and lost in the two cases.

The first collision with wet sand was with an almost entirely inelastic
medium, so correspondingly little of the energy was transmitted through
the medium and almost all of it was lost within it. In the second
collision, the pseudo-regolith was a much more elastic medium, so while
nevertheless some of the energy was so lost, much more of it was stored
briefly as distortions of the individual particles of the medium which
then rebounded back to their original shapes, thus releasing that energy
back out, some of it pushing down on the container, some of it lifting
some of the particles of the medium off the surface. Thus, in the
second test, the greater transmission of the energy through the medium
to displace the container, and the lifting of more of particles from the
surface, are both EFFECTS of the greater elasticity of the medium, and
therefore it is incorrect to say that either one of these two effects is
the cause of the other.

--

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I may be contacted via the contact address given on my website:
www.macfh.co.uk

Java Jive <java@evij.com.invalid> wrote:
> The error is that the law of conservation of momentum only applies with
> 'perfectly' elastic collisions, ...

Assuming translational invariance, conservation of momentum always
applies (although sometimes momentum can hide in odd places).

If a 1kg mass travelling at 2m/s hits and sticks to a stationary 1kg
mass; the resulting 2kg combined mass will travel at 1m/s, conserving
momentum. (I have assume all in-line motion). Because the sticky collision
is inelastic, we can lose kinetic energy (which might end up as heat
or sound, or some other type of energy).

However, in an elastic collision, an impactor mass (with some positive
momentum) might bounce *backwards* off the stationary mass, and so end
up with a negative momentum. This means that the impacted mass then
needs a positive momentum *greater* than than the pre-collision
momentum of the impactor. The sums are less easy, however, since you
need to satisfy conservation of energy as well.

Momentum is a vector, and is proportinal to velocity. Kinetic energy
is a scalar, and proportional to velocity squared, and so is always
positive.

#Paul

On 18/05/2023 12:55, #Paul wrote:
>
> Java Jive <java@evij.com.invalid> wrote:
>>
>> The error is that the law of conservation of momentum only applies with
>> 'perfectly' elastic collisions, ...
>
> Assuming translational invariance, conservation of momentum always
> applies (although sometimes momentum can hide in odd places).

Yes, my mistake, it's kinetic energy that is not conserved - Applied
Maths & Physics A-Levels were a very long time ago.

However, I think my description of what was happening in the video clips
is still correct, and I note that, so far at least, you haven't
questioned that.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 18/05/2023 16:37, Java Jive wrote:
> On 18/05/2023 12:55, #Paul wrote:
>>
>> Java Jive <java@evij.com.invalid> wrote:
>>>
>>> The error is that the law of conservation of momentum only applies with
>>> 'perfectly' elastic collisions, ...
>>
>> Assuming translational invariance, conservation of momentum always
>> applies (although sometimes momentum can hide in odd places).
>
> Yes, my mistake, it's kinetic energy that is not conserved  -  Applied
> Maths & Physics A-Levels were a very long time ago.
>
> However, I think my description of what was happening in the video clips
> is still correct, and I note that, so far at least, you haven't
> questioned that.
>
You said "Because conservation of momentum does not apply"

I disagree with that statement. Conservation of momentum always applies.

Conservation of kinetic energy does not - because some of it may be
converted into other forms, such as heat.

In the wet sand case after the collision we have effectively a single mass.

In the loose gravel case we have
* A large mass of the bucket and the ball
* A smaller mass of the "splashed" gravel which is moving upwards.

The splashed gravel has "negative" (upwards) momentum; which means the
ball-and-bucket will have more "positive" (downwards) momentum.

Andy

On 23/05/2023 11:18, Vir Campestris wrote:
> On 18/05/2023 16:37, Java Jive wrote:
>> On 18/05/2023 12:55, #Paul wrote:
>>>
>>> Java Jive <java@evij.com.invalid> wrote:
>>>>
>>>> The error is that the law of conservation of momentum only applies with
>>>> 'perfectly' elastic collisions, ...
>>>
>>> Assuming translational invariance, conservation of momentum always
>>> applies (although sometimes momentum can hide in odd places).
>>
>> Yes, my mistake, it's kinetic energy that is not conserved  -  Applied
>> Maths & Physics A-Levels were a very long time ago.
>>
>> However, I think my description of what was happening in the video
>> clips is still correct, and I note that, so far at least, you haven't
>> questioned that.
>>
> You said "Because conservation of momentum does not apply"
>
> I disagree with that statement. Conservation of momentum always applies.

Which I have admitted was an error, but in the quote above you have
conveniently omitted the fact that I then continued ...

"to understand what's really going on, you have to understand what's
happening to the kinetic energy of the impact. In both cases, while
some of it is transmitted through the medium into downwards momentum of
its container, a significant proportion of it is also lost as heat,
sound, and distortion of the medium surface, but the crucial point is
that, because the two mediums have different elasticities, different
amounts of it is being so transmitted and lost in the two cases."

.... and all that is true.

> In the wet sand case after the collision we have effectively a single mass.
>
> In the loose gravel case we have
> * A large mass of the bucket and the ball
> * A smaller mass of the "splashed" gravel which is moving upwards.
>
> The splashed gravel has "negative" (upwards) momentum; which means the
> ball-and-bucket will have more "positive" (downwards) momentum.

As already explained, both differences in behaviour - the greater
downward movement and the greater upward movement - are both *EFFECTS*
of the differing properties of the two mediums, so neither can be the
cause, and therefore also not the explanation, of the other. So far,
I've mentioned elasticity, but actually there are at least two more
properties of the mediums which are as or more important:

* The differing densities of the two mediums. Watching the clips,
although it's difficult to be sure, I think what was going on was that
two identical containers were filled nearly to the brim with the two
mediums, so the volume of material was constant for the two experiments,
but their differing densities would then mean that in the first
experiment the momentum imparted by the ball is being applied to a
larger mass than in the second, so you'd expect a smaller displacement
of the target for the first and a larger for the second, regardless of
any other considerations.

* The wet sand is held together by surface tension of the water between
the grains, and therefore is more self-cohesive, and therefore more
difficult to distort the surface of, and hence more kinetic energy is
lost in doing so, whereas the pseudo-regolith is less self-cohesive,
much more easily distorted, and therefore less kinetic energy is lost in
doing so.

So the situation is much more complex than implied in the clip, and
regardless of whichever of these three properties is predominant in
effect, the term 'momentum enhancement' seems to me to be quite wrong
for describing what is going on.

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

In article <u4ibsm$2i7c9$1@dont-email.me>, Java Jive
<java@evij.com.invalid> wrote:

> So the situation is much more complex than implied in the clip, and
> regardless of whichever of these three properties is predominant in
> effect, the term 'momentum enhancement' seems to me to be quite wrong
> for describing what is going on.

Question becomes, what term would be better?

All an interesting aside as it set me wondering about the effect of having
snooker balls that aren't so hard and rigid. 8-]

Jim

--
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Electronics https://www.st-andrews.ac.uk/~www_pa/Scots_Guide/intro/electron.htm
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On 24/05/2023 11:45, Jim Lesurf wrote:
>
> In article <u4ibsm$2i7c9$1@dont-email.me>, Java Jive
> <java@evij.com.invalid> wrote:
>>
>> So the situation is much more complex than implied in the clip, and
>> regardless of whichever of these three properties is predominant in
>> effect, the term 'momentum enhancement' seems to me to be quite wrong
>> for describing what is going on.
>
> Question becomes, what term would be better?

The problem with the term is can perhaps be posed as:
How can you 'enhance' something that is preserved?

What they're trying to do is to ensure that the target object is given
the maximum possible change in velocity from the impact, so perhaps any
of 'velocity maximisation' or 'momentum transfer efficiency' or 'impact
efficiency' would be better - I think my choice would be the last.
But I'm not sure that such a term is needed anyway, because in actual
practice the properties of the target would be an unalterable given,
although some very limited amount of control might be available through
choosing the point on the surface of it to hit - which I guess was the
point they were trying to make - but it would have to be somewhere
pretty much on the line of centres, because otherwise you'd waste much
of the kinetic energy of the impact merely in setting the target spinning!

> All an interesting aside as it set me wondering about the effect of having
> snooker balls that aren't so hard and rigid. 8-]

The relevant term there is 'coefficient of restitution':

https://en.wikipedia.org/wiki/Coefficient_of_restitution

For Applied Maths A-Level, we slogged through many questions on elastic
and inelastic impacts. Playing Bar Billiards in the pub next door, as
we were lining up shots, we used to joke "If the co-efficient of
restitution is 0.9, and the angle of impact is 45 degrees ..." but of
course no-one ever played a better ball from actually trying to
calculate anything like that, it was all a matter of skill derived from
experience. As far as I knew, for much of my time at the college until
I left, I held the record Bar Billiards break, which of course I've now
forgotten the actual amount of, such is how the vanity 'achievements' of
youth subsequently get rendered irrelevant by more important events in life!

--

Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

In article <u4l138$2vg03$1@dont-email.me>, Java Jive
<java@evij.com.invalid> wrote:
> > Question becomes, what term would be better?

> The problem with the term is can perhaps be posed as: How can you
> 'enhance' something that is preserved?

> What they're trying to do is to ensure that the target object is given
> the maximum possible change in velocity from the impact, so perhaps any
> of 'velocity maximisation' or 'momentum transfer efficiency' or 'impact
> efficiency' would be better - I think my choice would be the last.
> But I'm not sure that such a term is needed anyway, because in actual
> practice the properties of the target would be an unalterable given,
> although some very limited amount of control might be available through
> choosing the point on the surface of it to hit

I'd tend to go for either velocity 'maximisation' but 'enhanced' seems a
reasonable choice if defined clearly. May be clearer if velocity was used
here rather than momentum in the term as it indicates what was of interest.

> > All an interesting aside as it set me wondering about the effect of
> > having snooker balls that aren't so hard and rigid. 8-]

> The relevant term there is 'coefficient of restitution':

> https://en.wikipedia.org/wiki/Coefficient_of_restitution

But does that cover one of the 'balls' being able to break up in a way that
alters how much the 'target' velocity alters, making the dv larger?

> For Applied Maths A-Level, we slogged through many questions on elastic
> and inelastic impacts. Playing Bar Billiards in the pub next door, as
> we were lining up shots, we used to joke "If the co-efficient of
> restitution is 0.9, and the angle of impact is 45 degrees ...

FWIW we used to put coffee cups into the pocket-holes of metered tables so
we could ignore the time limit. 8-] Alas, no knowledge of basic Newtonian
mech allowed me to have any skill at snooker, etc.

Jim

--
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Audio Misc http://www.audiomisc.co.uk/index.html

On 23/05/2023 13:34, Java Jive wrote:
> On 23/05/2023 11:18, Vir Campestris wrote:
>> On 18/05/2023 16:37, Java Jive wrote:
>>> On 18/05/2023 12:55, #Paul wrote:
>>>>
>>>> Java Jive <java@evij.com.invalid> wrote:
>>>>>
>>>>> The error is that the law of conservation of momentum only applies
>>>>> with
>>>>> 'perfectly' elastic collisions, ...
>>>>
>>>> Assuming translational invariance, conservation of momentum always
>>>> applies (although sometimes momentum can hide in odd places).
>>>
>>> Yes, my mistake, it's kinetic energy that is not conserved  -
>>> Applied Maths & Physics A-Levels were a very long time ago.
>>>
>>> However, I think my description of what was happening in the video
>>> clips is still correct, and I note that, so far at least, you haven't
>>> questioned that.
>>>
>> You said "Because conservation of momentum does not apply"
>>
>> I disagree with that statement. Conservation of momentum always applies.
>
> Which I have admitted was an error, but in the quote above you have
> conveniently omitted the fact that I then continued ...
>
> "to understand what's really going on, you have to understand what's
> happening to the kinetic energy of the impact.  In both cases, while
> some of it is transmitted through the medium into downwards momentum of
> its container, a significant proportion of it is also lost as heat,
> sound, and distortion of the medium surface, but the crucial point is
> that, because the two mediums have different elasticities, different
> amounts of it is being so transmitted and lost in the two cases."
>
> ... and all that is true.
>
This time I'm going to quote you in full.

The reason I cut out the words on kinetic energy is that they are
irrelevant.

It is the conservation of momentum that matters. Only that.

>> In the wet sand case after the collision we have effectively a single
>> mass.
>>
>> In the loose gravel case we have
>> * A large mass of the bucket and the ball
>> * A smaller mass of the "splashed" gravel which is moving upwards.
>>
>> The splashed gravel has "negative" (upwards) momentum; which means the
>> ball-and-bucket will have more "positive" (downwards) momentum.
>
> As already explained, both differences in behaviour  -  the greater
> downward movement and the greater upward movement  -  are both *EFFECTS*
> of the differing properties of the two mediums, so neither can be the
> cause, and therefore also not the explanation, of the other.  So far,
> I've mentioned elasticity, but actually there are at least two more
> properties of the mediums which are as or more important:
>
> *  The differing densities of the two mediums.  Watching the clips,
> although it's difficult to be sure, I think what was going on was that
> two identical containers were filled nearly to the brim with the two
> mediums, so the volume of material was constant for the two experiments,
> but their differing densities would then mean that in the first
> experiment the momentum imparted by the ball is being applied to a
> larger mass than in the second, so you'd expect a smaller displacement
> of the target for the first and a larger for the second, regardless of
> any other considerations.
>
> *  The wet sand is held together by surface tension of the water between
> the grains, and therefore is more self-cohesive, and therefore more
> difficult to distort the surface of, and hence more kinetic energy is
> lost in doing so, whereas the pseudo-regolith is less self-cohesive,
> much more easily distorted, and therefore less kinetic energy is lost in
> doing so.
>
> So the situation is much more complex than implied in the clip, and
> regardless of whichever of these three properties is predominant in
> effect, the term 'momentum enhancement' seems to me to be quite wrong
> for describing what is going on.
>

That term made perfect sense to me, even though I had never heard it before.

Andy

On 26/05/2023 20:42, Vir Campestris wrote:
>
> On 23/05/2023 13:34, Java Jive wrote:
>>
>> So the situation is much more complex than implied in the clip, and
>> regardless of whichever of these three properties is predominant in
>> effect, the term 'momentum enhancement' seems to me to be quite wrong
>> for describing what is going on.
>
> That term made perfect sense to me, even though I had never heard it
> before.

It's an inherent self-contradiction: How can momentum be 'enhanced' if
it's preserved?

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On 26/05/2023 21:37, Java Jive wrote:
> On 26/05/2023 20:42, Vir Campestris wrote:
>>
>> On 23/05/2023 13:34, Java Jive wrote:
>>>
>>> So the situation is much more complex than implied in the clip, and
>>> regardless of whichever of these three properties is predominant in
>>> effect, the term 'momentum enhancement' seems to me to be quite wrong
>>> for describing what is going on.
>>
>> That term made perfect sense to me, even though I had never heard it
>> before.
>
> It's an inherent self-contradiction: How can momentum be 'enhanced' if
> it's preserved?
>
A small object hits the target asteroid, and transfers its momentum.

It hits it so hard that some debris is splashed backwards, as it would
be if it landed in water.

That debris has momentum in the opposite direction to the projectile.

Because the impact pushed debris in the opposite direction to the
projectile the momentum of the target has changed more than it would
from just the projectile.

Andy

On 28/05/2023 21:13, Vir Campestris wrote:
> On 26/05/2023 21:37, Java Jive wrote:
>> On 26/05/2023 20:42, Vir Campestris wrote:
>>>
>>> On 23/05/2023 13:34, Java Jive wrote:
>>>>
>>>> So the situation is much more complex than implied in the clip, and
>>>> regardless of whichever of these three properties is predominant in
>>>> effect, the term 'momentum enhancement' seems to me to be quite
>>>> wrong for describing what is going on.
>>>
>>> That term made perfect sense to me, even though I had never heard it
>>> before.
>>
>> It's an inherent self-contradiction: How can momentum be 'enhanced' if
>> it's preserved?
>
> A small object hits the target asteroid, and transfers its momentum.
>
> It hits it so hard that some debris is splashed backwards, as it would
> be if it landed in water.
>
> That debris has momentum in the opposite direction to the projectile.
>
> Because the impact pushed debris in the opposite direction to the
> projectile the momentum of the target has changed more than it would
> from just the projectile.

So momentum has been preserved, not enhanced.

[And, as already explained, both effects arise from properties of the
medium impacted, so neither can be considered the cause of the other.]

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Fake news kills!

I may be contacted via the contact address given on my website:
www.macfh.co.uk

On 28/05/2023 22:57, Java Jive wrote:
> On 28/05/2023 21:13, Vir Campestris wrote:
>> On 26/05/2023 21:37, Java Jive wrote:
>>> On 26/05/2023 20:42, Vir Campestris wrote:
>>>>
>>>> On 23/05/2023 13:34, Java Jive wrote:
>>>>>
>>>>> So the situation is much more complex than implied in the clip, and
>>>>> regardless of whichever of these three properties is predominant in
>>>>> effect, the term 'momentum enhancement' seems to me to be quite
>>>>> wrong for describing what is going on.
>>>>
>>>> That term made perfect sense to me, even though I had never heard it
>>>> before.
>>>
>>> It's an inherent self-contradiction: How can momentum be 'enhanced'
>>> if it's preserved?
>>
>> A small object hits the target asteroid, and transfers its momentum.
>>
>> It hits it so hard that some debris is splashed backwards, as it would
>> be if it landed in water.
>>
>> That debris has momentum in the opposite direction to the projectile.
>>
>> Because the impact pushed debris in the opposite direction to the
>> projectile the momentum of the target has changed more than it would
>> from just the projectile.
>
> So momentum has been preserved, not enhanced.
>

What they are intending to say is that the change of momentum of the
asteroid is greater than you get from the momentum of the projectile.

It's just semantics really!

> [And, as already explained, both effects arise from properties of the
> medium impacted, so neither can be considered the cause of the other.]
>
Agreed.

Andy

On 29/05/2023 11:21, Vir Campestris wrote:
>
> On 28/05/2023 22:57, Java Jive wrote:
>>
>> So momentum has been preserved, not enhanced.
>
> What they are intending to say is that the change of momentum of the
> asteroid is greater than you get from the momentum of the projectile.

Impossible, because then momentum would have been created, not preserved!

> It's just semantics really!

Semantics are important in science, and their poor use of words are
exactly what gave rise to my original complaint!

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Fake news kills!

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In article <u50io4$11hfv$1@dont-email.me>, Java Jive
<java@evij.com.invalid> wrote:
> > Because the impact pushed debris in the opposite direction to the
> > projectile the momentum of the target has changed more than it would
> > from just the projectile.

> So momentum has been preserved, not enhanced.

> [And, as already explained, both effects arise from properties of the
> medium impacted, so neither can be considered the cause of the other.]

However the desired outcome is momentum transfer (to the target)
'enhancement'. So perhaps "momentum transfer enhancement" is a fair term.
That said I suspect 'rocket scientists' would prefer "delta-V enhancement"
8-]

Jim

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In article <u5314r$1k8qs$1@dont-email.me>, Java Jive
<java@evij.com.invalid> wrote:
> > What they are intending to say is that the change of momentum of the
> > asteroid is greater than you get from the momentum of the projectile.

> Impossible, because then momentum would have been created, not preserved!

Note that momentum has a sign whereas kinetic energy does not. :-)

Jim

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On 30/05/2023 09:45, Jim Lesurf wrote:
> In article <u5314r$1k8qs$1@dont-email.me>, Java Jive
> <java@evij.com.invalid> wrote:
>>> What they are intending to say is that the change of momentum of the
>>> asteroid is greater than you get from the momentum of the projectile.
>>
>> Impossible, because then momentum would have been created, not preserved!
>
> Note that momentum has a sign whereas kinetic energy does not. :-)

Yes, but I was merely pointing out that what he said, still quoted
above, was probably not what he meant to say!

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